UNIVERSITY    OF   CALIFORNIA    PUBLICATIONS 

COLLEGE  OF  AGRICULTURE 

AGRICULTURAL  EXPERIMENT  STATION 

BERKELEY,  CALIFORNIA 


REPORT  OF  THE  PLANT  PATHOLOGIST 

AND 

SUPERINTENDENT  OF  SOUTHERN  CALIFORNIA  STATIONS 

JULY  1,  1906  TO  JUNE    30,   1909 

By  RALPH  E.  SMITH. 


BULLETIN  No.  203 

(Berkeley,  Cal.,  November,  1909) 


BERKELEY 

THE   UNIVERSITY   PRESS 
1909 


Benjamin  Ide  Wheeler,  Ph.D.,  LL.D,  President  of  the  University. 

EXPERIMENT    STATION     STAFF. 
E.  J.  Wickson,  M.A.,  Director  and  Horticulturist. 

E.  W.  Hilgard,  Ph.D.,   LL.D.,   Chemist. 
W.  A.   Setchell,   Ph.D.,   Botanist. 

Elwood  Mead,  M.S.,  C.E.,  Irrigation  Engineer.      (Absent  on  leave.) 

Leroy  Anderson,  Ph.D.,  Dairy  Industry  and  Superintendent  University  Farm  Schools. 

M.  E.  Jaffa,  M.S.,  Nutrition  Expert,  in  charge  of  the  Poultry  Station. 

R.  H.  Loughridge,  Ph.D.,  Soil  Chemist  and  Physicist. 

C.  W.  Woodworth,  M.S.,  Entomologist. 

G.  W.  Shaw,  M.A.,  Ph.D.,  Experimental  Agronomist  and  Agricultural  Technologist,  in  charge 
of  Cereal  Stations. 

George  E.  Colby,  M.S.,  Chemist   (Fruits,  Waters  and  Insecticides),  in  charge  of  Chem.  Lab. 

Ralph  E.  Smith,  B.S.,  Plant  Pathologist  and  Superintendent  of  Southern  California  Patho- 
logical Laboratory  and  Experiment  Station. 

F.  T.  Bioletti,  B.S.,  Viticulturist. 

A.  R.  Ward,  B.S.A.,  D.V.M.,  Veterinarian  and  Bacteriologist. 

E.  W.  Major,  B.Agr.,  Animal  Industry,   Farm  Manager,  University  Farm,  Davis. 

W.  T.  Clarke,   B.S.,  Assistant  Horticulturist  and  Superintendent  of  University  Extension  in 

Agriculture. 
H.  M.  Hall,  M.S.,  Assistant  Botanist. 

H.  J.  Quayle,  A.B.,  Assistant  Entomologist,  Plant  Disease  Laboratory,  Whittier. 
John  S.  Burd,  B.S.,  Chemist,  in  charge  of  Fertilizer  Control. 

C.  M.  Haring,   D.V.M.,  Assistant  Veterinarian  and  Bacteriologist. 
W.  B.  Herms,  M.A.,  Assistant  Entomologist. 

H.  A.  Hopper,  M.S. A.,  Dairy  Industry,  University  Farm,  Davis. 

E.  B.  Babcock,  B.S.,  Assistant  Agricultural  Education. 

W.  T.  Horne,  B.S.,  Assistant  Plant  Pathologist. 

J.  H.  Norton,  M.S.,  Assistant  Chemist,  in  charge  of  Citrus  Experiment  Station,  Riverside. 

J.  E.  Coit,  Ph.D.,  Assistant  Pomologist,  Plant  Disease  Laboratory,  Whittier. 

R.  E.  Mansell,  Assistant  in  Horticulture,  in  charge  of  Central  Station  grounds. 

Ralph  Benton,  B.S.,  B.L.,  Assistant  in  Entomology. 

D.  R.  Hoagland,   A.B.,   Assistant  in  Agricultural  Chemical  Laboratory. 
C.   B.  Lipman,   B.S.,  Assistant  in   Soil  Bacteriology. 

T.  F.  Hunt,  B.S.,  Assistant  Horticulturist. 

C.  O.  Smith,  M.S.,  Assistant  Plant  Pathologist,  Plant  Disease  Laboratory,  Whittier. 

E.  H.   Smith,  M.S.,  Assistant  Plant  Pathologist. 

E.  H.  Hagemann,  Assistant  in  Dairying,  Davis. 
Hans  C.  Holm,  B.S.,  Assistant  in  Zymology. 

R.  M.  Roberts,  B.S.A.,  Field  Assistant  in  Viticulture,  University  Farm,  Davis. 
Roscoe  Farrar,  B.S.,  Assistant  in  Soils  and  Farm  Crops,  University  Farm,  Davis. 

B.  S.  Brown,  B.S.A.,  Assistant  in  Horticulture,  University  Farm,  Davis. 
Howard  Phillips,  B.S.,  Assistant  in  Animal  Industry,  University  Farm,  Davis. 
L.  M.  Davis,  B.S.,  Assistant  in  Dairy  Husbandry,  University  Farm,  Davis. 

F.  L.  Yeaw,  B.S.,  Assistant  Plant  Pathologist,  University  Farm,  Davis. 
F.  D.  Hawk,  B.S.A.,  Assistant  in  Animal  Industry. 

A.  J.  Gaumnitz,  M.S.,  Assistant  in  Cereal  Investigations,   University  Farm,  Davis. 

S.   S.  Rogers,  Assistant  Plant  Pathologist,   Plant  Disease  Laboratory,  Whittier. 

P.  L.  McCreary,  B.S.,  Laboratory  Assistant  in  Fertilizer  Control. 

F.  E.  Johnson,  B.L.,  Assistant  in  Soil  Laboratory. 

M.  E.   Stover,  B.S.,   Assistant  in  Agricultural  Chemical  Laboratory. 

Charles  Fuchs,  Curator  Entomological  Museum. 

P.  L.  Hibbard,  B.S.,  Assistant  Fertilizer  Control  Laboratory. 

N.  D.  Ingham,  Assistant  in  Sylviculture,   Santa  Monica. 

J.  D.  Rose,  B.S.,  Assistant  in  Cereal  Laboratory. 

L.  Bonnet,  Assistant  in  Viticulture. 

Mrs.  D.  L.  Bunnell,  Clerk  to  the  Director. 

W.  H.  Volck,  Field  Assistant  in  Entomology,  Watsonville. 

E.  L.  Morris,  B.S.,  Field  Assistant  in  Entomology,  San  Jose. 

J.  S.  Hunter,  Field  Assistant  in  Entomology,  San  Mateo. 

John  Tuohy,  Patron, 

JOHN  T.  Bearss,  Foreman    ^  Tulare   Sub-station,   Tulare 


■  } 

J.  C.  Roper,  Patron,         "| 

E.  C.  Miller.  Foreman,   }  University  Forestry   Station,   Chico. 


REPORT  OF  THE  PLANT  PATHOLOGIST 

AND 

SUPERINTENDENT  OF  SOUTHERN  CALIFORNIA  STATIONS. 

July  1,  1906  to  June  30,  1909. 

BY 

EALPH  E.  SMITH. 


INTEODUCTOEY  AND   GENEEAL. 

At  the  beginning  of  the  period  covered  by  this  report,  July  1st, 
1906,  the  duties  of  the  plant  pathologist  were  increased  by  his  ap- 
pointment to  the  additional  position  of  Superintendent  of  the  South- 
ern California  Pathological  Laboratory  and  Experiment  Stations. 
By  this  action  the  Forestry  Station  at  Santa  Monica  and  the  Citrus 
Experiment  Station  at  Riverside  were  placed  in  charge  of  this  Divi- 
sion, as  well  as  the  Laboratory  of  Plant  Pathology  at  Whittier. 

The  Forestry  Station  is  a  local  sub-station  which  has  for  many 
years  been  under  the  control  of  the  University,  as  one  of  the  several 
substations  which  were  formerly  conducted  by  the  Agricultural  Ex- 
periment Station. 

The  Citrus  Experiment  Station  constitutes  a  branch  of  the  work 
founded  under  the  legislative  act  of  1905,  in  connection  with  the 
Southern  California  Pathological  Laboratory.  The  idea  of  this  con- 
solidation of  the  three  local  branches  was  to  handle  all  the  sub-station 
work  in  southern  California  under  one  management.  Shortly  before 
this  time  the  old  sub-station  located  near  Pomona  was  given  up  and 
the  land  reverted  to  the  original  owner,  the  work  being  carried  on 
to  better  advantage  by  the  newly  created  stations. 

With  the  development  of  the  Division  of  Plant  Pathology  during 
the  six  years  of  its  existence  the  demand  for  plant  disease  investiga- 
tion has  more  than  kept  pace.  The  present  report  extends  from  July 
1st,  '06  to  June  30th,  '09,  covering  a  period  composed  of  the  second 
year  of  one  biennial  legislative  period  and  the  whole  of  another.  The 
work  of  this  time  has  therefore  been  divided  into  two  quite  distinct 


6  UNIVERSITY  OF  CALIFORNIA EXPERIMENT  STATION. 

portions.  The  year  '06- '07,  being  the  second  year  of  the  period  from 
July,  '05  to  July,  '07,  was  occupied  by  this  Division  largely  in  the 
continuation  of  several  special  investigations,  founded  on  appropria- 
tions of  the  legislature  of  1905,  which  have  already  been  reported 
on  up  to  July,  '06,  in  our  last  report.  (Bulletin  No.  184,  Report  of 
the  Plant  Pathologist  to  July  1,  1906.)  These  were  the  Pear  Blight 
work,  established  by  a  special  appropriation  of  $10,000  for  this  pur- 
pose, the  Walnut  Blight  investigation,  also  provided  for  by  the  State 
with  a  $4,000  appropriation,  the  Beet  Blight  investigation,  supported 
by  a  private  subscription  of  $1,000  raised  by  the  Spreckels  Sugar 
Company,  and  the  Lemon  Rot  investigation,  carried  on  under  a  fund 
of  $1,000  contributed  by  the  lemon  interests  of  southern  California. 

During  the  first  year  covered  by  the  present  report  the  activities 
of  the  Division  were  largely  confined  to  these  special  undertakings 
by  force  of  circumstances.  Funds  in  the  amounts  specified  were 
fairly  liberal  to  support  the  work,  half  of  each  amount  being  available 
for  the  year  '06- '07,  but  it  was  impossible  to  pay  much  attention  to 
other  work. 

During  the  period  of  these  special  appropriations  from  1905  to 
1907  it  became  very  evident  that  such  a  method  of  financial  support 
for  the  investigation  of  plant  diseases  is  far  from  ideal.  The  result 
has  been  that  while  it  was  possible  to  give  a  large  amount  of  atten- 
tion to  these  problems  during  the  period  covered  by  the  appropria- 
tions, it  was  impossible  to  lay  out  the  work  and  develop  the  Division 
on  a  permanent  basis  or  put  it  into  good  shape  for  continuous,  satis- 
factory work  on  whatever  problems  might  arise.  At  the  end  of  the 
fiscal  year  '06- '07  this  Division  had  at  its  disposal  a  considerable 
number  of  well-trained  assistants  who  had  become  experienced  in 
work  in  California  and  who  would  have  been  of  great  and  increasing 
value  for  continued  work  in  the  investigation  of  different  plant  dis- 
eases or  other  lines  of  agricultural  experimentation.  As  a  result, 
however,  of  the  discontinuance  of  these  special  investigations  on 
pear  blight,  etc.,  at  the  end  of  the  biennial  period,  no  funds  were 
available  for  keeping  up  this  working  force  and  they  were  lost  to 
the  Station.  Moreover,  it  is  extremely  difficult  to  secure  competent 
help  for  these  limited  periods  of  special  work  with  no  guarantee  of 
regular  continuance.  It  is  certain  that,  with  each  succeeding  legis- 
lature, demands  will  be  made  for  appropriations  to  support  work  of 
the  nature  carried  on  by  this  Division  in  one  part  of  the  State  or 
another.  Yet  under  the  conditions  described  it  is  impossible  to  main- 
tain an  efficient  organization  for  meeting  these  varying  demands  at 
short  notice. 


Bulletin  203.  REPORT  OF  PLANT  PATHOLOGIST.  7 

A  most  satisfactory  remedy  for  this  condition  was  found  for  the 
southern  part  of  the  State  in  the  establishment  of  the  Southern  Cali- 
fornia Pathological  Laboratory.  This  institution,  founded  by  the 
legislature  of  1905  and  now  established  in  full  working  order,  is 
maintained  by  regular  appropriations  like  other  State  institutions, 
and  may  thus  be  administered  efficiently  and  economically  to  carry 
on  continuous  work  on  the  most  important  problems  which  present 
themselves,  with  no  embarrassing  limitations  or  violent  fluctuations 
in  the  available  funds.  The  Laboratory  has  been  housed  in  a  perma- 
nent building  at  Whittier,  is  well  equipped  for  its  purpose,  has  a 
permanent,  well-organized  working  force  and  is  thus  able  to  cover 
this  field  with  increasing  satisfaction  and  with  much  economy  to  the 
State,  as  compared  with  the  system  of  irregular  appropriations  for 
specific  investigations  or  for  seeking  cures  for  certain  troubles. 

Previous  to  the  meeting  of  the  legislature  of  1907  a  considerable 
variety  of  undertakings  was  urged  upon  the  Division  with  the  object 
of  seeking  special  appropriations  for  their  support.  This  included 
the  continuation  of  the  pear  blight  work,  work  on  the  peach  blight, 
a  disease  which  had  suddenly  assumed  very  serious  proportions,  de- 
mands for  local  laboratories  in  a  number  of  sections,  suggested  by 
the  establishment  of  the  Southern  California  Laboratory,  and  a  va- 
riety of  other  projects.  So  numerous  and  varied  were  these  sugges- 
tions that  much  confusion  would  have  resulted  had  they  all  been 
presented  to  the  legislature  in  the  form  of  special  appropriation  bills, 
and  the  carrying  out  in  such  a  form  of  the  work  desired  would  have 
been  most  unwieldy.  It  was  therefore  thought  best  to  combine  all 
these  projects  into  one  bill,  asking  for  an  appropriation  to  cover  gen- 
eral work  in  plant  pathology  outside  of  southern  California  along 
the  same  lines  as  had  proven  so  successful  in  that  section.  It  was 
proposed  that  the  office  of  State  Plant  Pathologist  be  created  for  the 
plant  pathologist  of  the  Experiment  Station  and  that  the  laboratory 
at  Berkeley  be  designated  the  State  Laboratory  of  Plant  Pathology, 
thus  putting  all  the  work  of  this  sort  in  the  State  upon  a  uniform 
basis.  This  bill  passed  the  legislature  but  failed  to  receive  the  Gov- 
ernor's signature.  As  it  represented  all  the  special  lines  of  work 
which  had  been  going  on  during  the  previous  period,  as  well  as  the 
demands  which  had  been  made  on  the  Division  for  the  following  two 
years,  the  whole  work  was  seriously  crippled  and  very  much  limited 
during  the  period  from  July  1st,  1907  to  June  30th,  1909.  Such 
work  as  has  been  possible  during  that  time  has  been  only  such  as 
could  be  provided  for  by  the  general  Experiment  Station  or  Univer- 
sity funds,  with  the  exception  of  that  done  in  southern  California. 


8  UNIVERSITY  OF   CALIFORNIA EXPERIMENT   STATION. 

Some  activity  has  also  been  going  on  with  funds  derived  from  the 
Adams  Fund,  a  national  grant  made  for  the  purpose  of  agricultural 
investigation. 

The  bringing  about  of  the  arrangement,  found  so  successful  in 
southern  California,  for  the  remainder  of  the  State  was  provided  by 
the  legislature  of  1909  by  the  passage  of  the  following  Act: 

''An  act  providing  for  the  investigation  of  the  nature  and  means  of  control 
of  destructive  diseases  of  cultivated  plants  in  those  portions  of  the  state  not 
benefited  by  the  Southern  California  Pathological  Laboratory,  and  making  an 
appropriation  therefor. 

' '  The  people  of  the  State  of  California,  represented  in  senate  and  assembly, 
do  enact  as  follows: 

"Section  1.  The  regents  and  president  of  the  University  of  California  are 
hereby  directed  to  maintain*  in  connection  with  the  agricultural  experiment  work 
of  the  university  in  those  portions  of  the  state  not  benefited  by  the  Southern 
California  Pathological  Laboratory  a  scientific  station  or  laboratory  with  the 
necessary  equipment  for  the  investigation  of  the  nature  and  means  of  control 
of  injurious  and  destructive  diseases  of  cultivated  trees,  plants  and  crops. 

"Section  2.  They  are  directed  to  make  or  cause  to  be  made  investigations 
of  such  troubles  as  pear  blight,  peach  blight,  olive  knot,  apricot  failures,  pear 
scab,  apple  diseases,  root  rot,  root  knot,  diseases  of  tomatoes,  potatoes,  asparagus, 
onions  and  other  vegetables,  and  such  other  plant  diseases  as  may  be  called  to 
their  attention.  They  shall  also  furnish  information  and  practical  demonstrations 
to  the  growers  of  these  crops  as  to  the  best  means  of  control  for  such  diseases. 

"Section  3.  The  sum  of  fifteen  thousand  dollars  is  hereby  appropriated  out 
of  any  money  in  the  state  treasury  not  otherwise  appropriated  to  be  expended 
by  the  regents  of  the  University  of  California  in  carrying  out  the  purposes  of 
this  act  and  the  state  controller  is  hereby  authorized  and  directed  to  draw  his 
warrant  for  the  same,  payable  to  the  regents  of  the  University  of  California,  and 
the  treasurer  of  the  state  is  hereby  directed  to  pay  such  warrant. ' ' 

Under  this  law  it  will  be  possible  to  commence  systematic  investi- 
gations and  demonstrations  on  the  most  serious  plant  disease  prob- 
lems in  northern  California,  and  this  work  is  now  being  actively  or- 
ganized. The  law  is  intended  to  provide  for  permanent  work  similar 
to  that  in  southern  California,  and  it  is  hoped  that  the  results  of 
this  work  may  be  such  as  to  warrant  continued  financial  support  of 
the  State  in  the  future,  thus  maintaining  at  the  University,  in  reality 
as  well  as  in  name,  the  headquarters  of  the  division  of  plant  pathology. 

In  connection  with  this  work  the  establishment  of  the  University 
Farm  at  Davis  has  considerable  promise.  It  is  expected  that  oppor- 
tunities will  develop  at  the  Farm  for  field  work  and  practical  opera- 
tions of  various  sorts  on  a  larger  scale  than  can  be  handled  at 
Berkeley,  a  very  necessary  feature  in  work  of  this  kind. 

A  very  gratifying  feature  of  the  development  of  work  in  plant 
pathology  in  California  is  the  increasing  tendency  to  affiliate  the  work 


Bulletin  203.  REPORT  OF  PLANT  PATHOLOGIST.  9 

with  that  of  the  various  Divisions  of  the  United  States  Department  of 
Agriculture.  The  rapid  development  of  the  Federal  Department  has 
resulted  during  recent  years  in  a  great  increase  in  its  activities  in 
California.  It  has  been  the  aim  of  this  Division  to  so  conduct  its 
work  as  to  operate  completely  in  harmony  with  the  agents  of  the 
Department  and  avoid  as  much  as  possible  any  duplication  of  work 
or  misunderstanding.  It  is  believed  that  the  best  results  may  be 
secured  by  segregation  of  the  various  workers  on  different  problems 
or  different  phases  of  the  same  problem,  rather  than  an  attempt  at 
combined  work  upon  the  same  subject.  So  long  as  a  clear  understand- 
ing exists  as  to  the  plans  and  undertakings  of  the  Station  and  the 
Department,  there  is  no  obstacle  to  harmonious  work,  and  the  field 
is  broad  enough  for  the  utilization  of  every  possible  agency  which  can 
be  brought  into  action.  It  is  particularly  undesirable,  however,  that 
representatives  of  the  State  Station  and  those  of  the  United  States 
Department  should  be  working  in  the  same  field  along  more  or  less 
similar  lines  without  such  an  understanding  and  a  complete  mutual 
knowledge  of  what  is  being  undertaken. 

The  correspondence  of  the  Division  is  continually  growing,  in- 
volving a  great  variety  of  questions  regarding  all  sorts  of  troubles 
with  plants,  which  leads  to  a  continual  broadening  of  the  experience 
of  those  connected  with  the  work.  The  practice  of  personal  inspec- 
tion on  the  part  of  the  plant  pathologist  and  his  assistants,  requiring 
a  large  amount  of  traveling  to  various  parts  of  the  State,  is  consid- 
ered highly  desirable  for  work  of  this  sort.  Though  much  time  is 
consumed  in  this  way,  it  is  impossible  otherwise  to  keep  in  touch 
with  agricultural  conditions  in  a  State  of  the  size  and  peculiarities 
of  California.  The  establishment  of  the  Southern  California  Labora- 
tory has  been  of  great  advantage  in  this  respect,  furnishing  a  local 
headquarters  for  the  work  in  one  of  the  most  important  sections  of 
the  State. 

The  publications  issued  by  this  Division  during  the  period  cov- 
ered by  this  report  include  Bulletin  184,  Report  of  the  Plant  Pathol- 
ogist to  July  1,  1906;  Bulletin  190,  The  Brown  Rot  of  the  Lemon; 
Bulletin  191,  California  Peach  Blight;  Bulletin  196,  Eucalyptus  in 
California;  Bulletin  200,  Gum  Disease  of  Citrus  Trees  in  California; 
and  Circular  35,  The  Southern  California  Pathological  Laboratory 
and  Citrus  Experiment  Station.  Numerous  communications  on  sub- 
jects connected  with  the  work  have  appeared  in  the  horticultural  press 
from  members  of  the  staff,  as  well  as  contributions  to  the  programs 
of  Farmers'  Institutes,  Fruit  Growers'  Conventions,  Farmers'  Clubs, 
and  other  meetings  of  a  similar  nature. 


10  UNIVERSITY  OF  CALIFORNIA EXPERIMENT  STATION. 

Changes  in  the  staff  of  the  Division  have  been  too  frequent,  mostly 
on  account  of  the  demands  of  the  special  appropriations  covering  the 
year  1906-7  and  the  discontinuance  of  these  appropriations  after  that 
time.  Messrs.  R.  L.  Adams,  S.  S.  Rogers  and  F.  L.  Yeaw  joined  the 
pear  blight  work  during  the  year  mentioned.  The  two  former  have 
since  entered  the  employ  of  the  Spreckels  Sugar  Company,  in  charge 
of  a  private  experiment  station  established  by  that  company.  Mr. 
Yeaw  reentered  the  service  of  this  Division  in  December,  1907.  Mr. 
A.  M.  West  resigned  his  position  as  Assistant  Plant  Pathologist  in 
the  Southern  California  Laboratory  on  November  1st,  1906.  Mr.  B. 
J.  Jones,  who  was  connected  with  the  pear  blight  work  during  the 
whole  biennial  period  and  who  had  charge  of  the  field  work  during 
the  most  of  the  time,  left  the  Division  on  the  conclusion  of  this  work. 
Mr.  CO.  Smith  was  transferred  from  Berkeley  to  the  Whittier  Lab- 
oratory in  December,  1906.  Mr.  E.  B.  Babcock,  formerly  a  member 
of  our  staff,  returned  to  the  work  in  July,  1907.  He  was  stationed  in 
southern  California  for  a  time  and  afterwards  engaged  in  teaching 
at  the  University,  being  appointed  Assistant  Professor  of  Plant 
Pathology  on  July  1st,  1908.  July  1st,  1909,  Mr.  Babcock  was  trans- 
ferred from  plant  pathology  to  another  department  of  the  University. 
The  vacancy  in  teaching  thus  created  has  been  filled  by  the  appoint- 
ment, as  Assistant  Professor  of  Plant  Pathology,  of  Mr.  William  T. 
Home,  Chief  of  the  Department  of  Plant  Pathology  in  the  Agricul- 
tural Experiment  Station  of  Cuba.  Mr.  T.  F.  Hunt,  who  had  been 
employed  in  the  work  on  pear  blight  and  beet  blight,  was  assigned 
to  the  Citrus  Experiment  Station  at  Riverside  in  September,  1906. 
On  July  1st,  1909,  he  was  transferred  to  the  position  of  chief  field 
assistant  in  the  northern  California  work.  Mr.  O.  Butler,  a  graduate 
student  in  plant  pathology,  was  employed  in  research  work  in  the 
Southern  California  Laboratory  from  August,  1907,  to  January,  1909. 
Mr.  H.  J.  Ramsey,  who  has  been  stationed  at  the  Southern  California 
Laboratory,  at  Whittier,  as  chief  assistant  during  the  whole  period 
of  this  report,  was  advanced  in  title  to  Assistant  Professor  of  Plant 
Pathology  on  July  1st,  1909.  Miss  E.  H.  Smith  has  had  charge  of 
office  and  laboratory  work  at  Berkeley  as  heretofore.  Mr.  II.  J. 
Quayle,  Assistant  Professor  of  Entomology  in  the  University,  was  as- 
signed to  the  southern  Laboratory  for  entomological  work,  commenc- 
ing July  1st,  1908.  Mr.  J.  W.  Mills,  for  many  years  in  charge  of 
university  sub-station  work  in  southern  California,  was  assigned  to 
the  Citrus  Experiment  Station  at  Riverside  upon  the  beginning  of 
the  work  there  in  June.  1906.  Mr.  Mills  continued  in  local  charge 
of  the  development  of  the  Station  grounds  until  July  1st,  1908,  when 


Bulletin  203.  REPORT  OP  PLANT  PATHOLOGIST.  11 

he  resigned  to  engage  in  private  enterprise.  Mr.  J.  H.  Norton,  Chem- 
ist at  the  Arkansas  Station,  was  appointed  Assistant  Professor  of 
Fertilization  on  July  1st,  1908,  and  assigned  to  work  in  southern 
California  on  problems  of  soil  fertilization  and  management,  particu- 
larly with  reference  to  the  citrus  industry.  On  July  1st,  1909,  Mr. 
Norton's  title  was  changed  to  that  of  Assistant  Professor  of  Agricul- 
tural Chemistry.  Mr.  N.  D.  Ingham,  formerly  employed  in  the  pear 
blight  work  of  this  Division,  was  assigned  to  the  Santa  Monica  For- 
estry Station  in  April,  1906,  and  still  continues  in  charge  of  that 
work.  Mr.  W.  B.  Parker,  a  University  student,  was  employed  during 
the  summer  of  1908  in  the  olive  knot  investigation.  Dr.  J.  Eliot  Coit, 
of  the  Arizona  Experiment  Station,  was  appointed  Assistant  Professor 
of  Pomology  from  July  1st,  1909,  and  assigned  to  citrus  work  in  south- 
ern California. 


REPORT  ON  WORK  OF  THE  DIVISION. 

The  principal  subjects  considered  in  this  report  are  as  follows : 
Plant  Pathology  at  the  University,  Development  of  the  Whittier 
Laboratory,  Development  of  the  Riverside  Station,  Condition  of  the 
Forestry  Station,  Pear  Blight,  Walnut  Blight  and  Culture,  Lemon 
Rot,  Sugar-Beet  Blight,  Peach  Blight,  Rose  Diseases,  Apricot  Diseases, 
Olive  Knot,  Onion  Mildew,  Brown  Rot  of  Stone  Fruits,  Celery  Blight, 
Apple  Mildew,  Tomato  Diseases,  Technical  Investigations  in  Plant 
Pathology,  Work  in  Entomology  at  the  Southern  California  Labora- 
tory, Citrus  Culture  and  Diseases  (Disease  Investigation,  Soil  and  Fer- 
tilizer Work,  Pomological  Work),  Variety  Introduction  and  Testing 
of  Pecans,  Peaches  and  Tomatoes,  Eucalyptus  Investigations,  Work 
in  Imperial  Valley,  Pasadena  City  Farm. 

PLANT   PATHOLOGY   AT    THE   UNIVEKSITY. 

While  the  headquarters  of  this  Division  are  naturally  at  the  Uni- 
versity in  Berkeley,  it  has  not  yet  been  possible  to  develop  the  work 
there  in  a  satisfactory  degree.  The  funds  available  for  this  work 
have  been  so  much  more  abundant  in  connection  with  the  Southern 
California  Laboratory  than  those  for  the  remainder  of  the  State  that 
the  former  institution  has  come  to  be  the  principal  field  of  the  work 
of  this  Division.  The  teaching  of  plant  pathology  at  the  University 
has  never  received  the  attention  which  the  subject  deserves.  Courses 
have  been  given  in  a  somewhat  desultory  manner  since  1904  by  the 
writer  and  Messrs.  C.  O.  Smith  and  Babcock.  Commencing  in  1908 
the  work  received  more  systematic  attention  than  before  through  the 


12  UNIVERSITY  OF  CALIFORNIA EXPERIMENT  STATION. 

appointment  of  Mr.  Babcock  as  assistant  professor  of  plant  pathology. 
The  department,  however,  has  never  been  sufficiently  equipped  or 
housed  to  give  extended  or  specialized  instruction  in  this  subject.  In 
the  field  of  investigation  the  work  has  also  suffered  in  a  similar 
manner.  Following  the  early  work  of  the  writer  from  1903  to  1905, 
carried  on  with  practically  no  equipment  or  assistance,  the  following 
two  years  were  devoted,  as  mentioned  elsewhere  in  this  report,  to 
certain  special  investigations  on  a  considerable  scale,  but  without 
the  means  for  general  development  of  the  department  at  the  Univer- 
sity. Some  progress  was  made,  however,  during  this  period  in  the 
development  of  laboratory  equipment  and  other  facilities.  During 
the  past  two  years  there  has  been  very  little  more  accomplished  in 
this  direction.  Investigations  have  been  carried  on  by  Miss  Smith 
in  the  laboratory  and  Mr.  Yeaw  in  the  field,  and  some  problems  have 
also  been  taken  up  by  Mr.  Babcock,  but  the  development  and  activity 
of  the  department  outside  of  southern  California  during  this  time 
has  been  very  limited. 

Conditions  for  the  future,  both  in  regard  to  investigation,  experi- 
mental work  and  teaching  at  the  University  are  much  more  promising. 
Professor  Home  has  been  called  for  the  purpose  of  assisting  in  build- 
ing up  the  teaching  department,  and  the  facilities  and  equipment  for 
this  purpose  are  rapidly  improving.  It  seems  safe  to  predict  that  the 
teaching  of  plant  pathology  at  the  University  will  from  now  on  re- 
ceive very  satisfactory  consideration. 

The  situation  in  regard  to  investigation  and  experimentation,  to- 
gether with  field  work  on  plant  diseases,  in  the  northern  part  of  the 
State  is  entirely  changed  and  very  much  improved  by  the  action  of 
the  legislature  in  passing  the  bill  referred  to  on  page  eight.  This  work 
will  be  centered  at  the  University  and  to  some  extent  at  the  Davis 
Farm  and  can  now  be  carried  on  upon  a  systematic  and  permanent 
basis.  In  general,  therefore,  it  may  be  said  that  the  Division  is  at 
last  finding  itself  in  a  position  to  make  its  headquarters  at  the  Uni- 
versity where  they  properly  belong  and  administer  its  work  in  a 
logical  manner  all  over  the  State. 

DEVELOPMENT   OF   THE   WHITTIER  LABORATORY. 

The  establishment  of  the  Whittier  and  Riverside  branches  of  the 
Station  work  has  been  described  in  Circular  35  of  this  Station.  Since 
this  publication  the  work  of  development  at  Whittier  has  gone  on 
satisfactorily  both  in  the  laboratory  building  and  the  adjacent  grounds. 
The  laboratory  is  now  well  equipped  for  the  work  of  investigation  in 
plant  pathology,  entomology,  and  to  some  extent  in  chemistry.     An 


Bulletin  203. 


REPORT  OF  PLANT  PATHOLOGIST. 


13 


appropriation  of  $1500  was  made  by  the  last  legislature  for  the  further 
equipment  of  this  laboratory,  and  with  this  money  we  intend  to  supply 
several  urgent  needs.  A  considerable  part  of  the  appropriation  will 
be  expended  in  the  purchase  of  books,  with  the  idea  of  obtaining  a 
working  library  composed  of  the  most  necessary  works  needed  by 
those  engaged  in  the  laboratory  investigations.  The  remainder  of  the 
appropriation  will  be  used  in  the  purchase  of  a  few  more  microscopes, 


Fig.  1. — Experimental  Garden  at  Whittier  Laboratory.     May,  1908. 

a  high-class  photographic  lens,  and  other  necessary  equipment.  In  con- 
nection with  the  library  a  good  beginning  has  been  made  toward  col- 
lecting as  complete  a  set  as  possible  of  the  publications  of  the  various 
state  experiment  stations  and  the  United  States  Department  of  Agri- 
culture. The  library  receives  regularly  all  the  current  publications 
of  these  institutions,  and  a  fairly  complete  set  of  back  numbers  is 
being  collected.  These  bulletins  have  all  been  catalogued  and  systemat- 
ically arranged. 

During  the  last  two  seasons  most  of  the  available  field  space  at 
the  laboratory  has  been  utilized  in  growing  walnuts.  Considerable 
plantings  have  been  made  of  various  species  and  selections  for  the 
purpose  of  forming  grafting  stock  for  trees  of  improved  quality  to 
be  grown  and  distributed  by  the  Station  for  practical  trial  by  walnut 


14 


UNIVERSITY  OF  CALIFORNIA EXPERIMENT  STATION. 


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Bulletin  203.  REPORT  OF  PLANT  PATHOLOGIST.  15 

growers  in  various  sections.  Considerable  space  has  also  been  devoted 
to  tomatoes  in  connection  with  the  work  on  this  vegetable.  A  limited 
number  of  specimen  trees  have  been  planted  in  the  space  available, 
representing  the  most  important  varieties  of  citrus  and  other  fruits. 
A  grove  of  walnut  and  other  nut  trees  planted  on  the  near-by  grounds 
of  the  Whittier  State  School  is  developing  well  and  will  soon  afford 
an  interesting  and  valuable  feature. 

During  the  past  year  the  development  and  equipment  of  the  labora- 
tory has  been  considerably  advanced  by  the  addition  of  Professor 
Quayle's  work  in  entomology.  Two  rooms  on  the  second  floor  of  the 
building  have  been  devoted  to  this  purpose  and  equipped  as  an  office 
and  laboratory  for  the  entomologist.  A  portion  of  the  greenhouse  has 
also  been  set  aside  for  an  insectary  and  used  by  Professor  Quayle  in 
his  work.  A  considerable  amount  of  apparatus  has  been  added  to 
the  laboratory  equipment  for  entomological  purposes. 

In  the  same  connection  may  be  mentioned  the  equipment  of  a  small 
but  quite  complete  chemical  laboratory  in  one  of  the  larger  rooms  on 
the  second  floor  of  the  building.  This  room  has  been  fitted  with 
benches,  shelves,  cupboards,  hood,  etc.,  and  equipment  is  now  being 
installed  for  chemical  work. 

DEVELOPMENT  OF  THE  BTVEBSIDE  STATION. 

Work  on  the  grounds  at  Riverside  is  proceeding  well  and  the 
plantings  thus  far  are  developing  very  satisfactorily.  The  nature  of 
the  work  undertaken  at  this  Station  precludes  the  possibility  of  the 
rapid  development  and  progress  made  at  the  Whittier  Laboratory,  but 
every  effort  is  being  put  forth  to  develop  this  Station.  The  plantings 
of  young  citrus  trees  made  in  the  spring  of  1907  for  fertilizer  and 
other  experiments,  as  described  in  Circular  35  and  elsewhere  in  this 
report,  are  making  an  excellent  development.  The  citrus  seed-bed 
stock  started  in  1907  has  been  planted  out  in  nursery  form  and 
budded  to  various  selected  stock;  a  considerable  planting  of  euca- 
lyptus trees  of  various  species  has  been  made  on  the  mountainside 
back  of  the  Station;  improvements  in  the  irrigation  facilities  have 
been  made  from  time  to  time,  and  much  other  work  of  a  general  nature 
has  been  done  in  developing  and  beautifying  these  grounds.  The 
lines  of  investigation  centered  at  this  Station  have  been  particularly 
those  connected  with  field  problems  in  citrus  culture,  matters  having 
to  do  with  studies  of  soil  nature  and  treatment  and  pomological 
work.  It  is  for  such  purposes  that  the  orchard  and  nursery  plantings 
on  the  place  have  been  made.  In  connection  with  Professor  Norton's 
work  further  development  of  field  and  cultural  work  is  being  laid 


16 


UNIVERSITY  OF  CALIFORNIA EXPERIMENT  STATION. 


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Bulletin  203.  REPORT  OF  PLANT  PATHOLOGIST.  17 

out  and  a  system  of  pot  cultures  is  also  being  installed  on  a  consid- 
erable scale.  Much  of  the  work  of  this  Station  is  necessarily  carried 
on  in  the  commercial  groves  of  the  vicinity  and  elsewhere  rather  than 
on  the  Station  grounds  proper. 

An  effort  was  made  during  the  meeting  of  the  last  legislature  to 
obtain  an  appropriation  for  erecting  a  laboratory  and  office  building 
on  the  Station  grounds,  but  owing  to  the  fact  that  this  land  is  not 
owned  by  the  State  but  held  on  a  twenty  years'  lease,  no  appropria- 
tion for  a  building  was  granted.  Some  effort  was  also  made  to  obtain 
an  appropriation  for  the  purchase  of  the  land  by  the  State,  but  this 
met  with  little  support  on  account  of  the  high  value  of  the  property, 
due  to  its  favorable  location. 

CONDITION  OF   THE   FORESTRY  STATION. 

At  the  time  when  the  Santa  Monica  Station  was  turned  over  to 
this  Division  all  the  buildings  of  the  Station  had  been  lost  by  fire, 
and  the  new  ones,  for  which  plans  had  been  prepared,  had  not  yet 
been  begun.  The  erection  of  these  buildings  was  therefore  the  chief 
activity  of  the  Station  during  the  first  year  covered  by  this  report. 
Two  dwelling  houses,  a  stable,  tank  house,  lath  house,  green  house  and 
office  were  erected,  so  that  the  Station  is  now  excellently  equipped  as 
to  buildings.  Much  improvement  in  the  grounds  has  been  made  by 
Mr.  Ingham  by  cleaning  up  dead  trees,  underbrush  and  other  relics 
of  the  disastrous  fire  which  destroyed  the  former  buildings,  as  well 
as  by  new  plantings,  road  making,  etc.  In  point  of  natural  beauty 
and  picturesqueness  of  location,  the  Forestry  Station  may  be  called 
the  choicest  of  the  University's  possessions.  The  valuable  collection 
of  growing  eucalyptus  trees  on  the  Station  grounds,  representing  over 
seventy  species,  as  well  as  many  other  trees  and  shrubs,  was  not  seri- 
ously injured  by  the  fire,  and  this  unique  collection  represents  the 
most  valuable  feature  of  the  Station. 

The  work  of  the  Forestry  Station  in  previous  years  has  consisted 
largely  in  the  growing  and  public  distribution  of  eucalyptus  trees  of 
various  species  in  order  to  promote  their  trial  and  planting  through- 
out the  State.  Since  all  the  promising  species  can  now  be  obtained 
of  nurserymen,  and  with  the  limited  funds  devoted  to  the  work  of 
this  Station,  it  has  seemed  unwise  to  continue  this  tree  distribution 
during  the  period  covered  by  this  report.  On  the  Station  grounds, 
therefore,  little  has  been  attempted  except  in  the  way  of  keeping  up 
the  property  and  using  the  collection  of  trees  growing  there  for  pur- 
poses of  study  and  observation. 

It  is  evident  that  in  the  field  of  forestry  proper  this  Station  can 


18  UNIVERSITY  OF  CALIFORNIA — EXPERIMENT  STATION. 

be  put  to  no  important  use  under  present  conditions.  Extensive  work 
in  forestry  is  being  done  in  southern  California  by  the  United  States 
Forest  Service  to  much  better  advantage  than  could  be  done  by  the 
State  Experiment  Station.  The  equipment  at  Santa  Monica  presents, 
moreover,  no  particular  advantage  for  such  a  purpose.  The  Station 's 
greatest  field  of  usefulness  is  rather  in  the  direction  of  sylviculture, 
in  the  study  of  planting  and  growing  of  trees  as  a  commercial  crop, 
for  which  some  of  the  various  species  of  eucalyptus  are  of  great  value 


Fig.  4 — Santa  Monica  Forestry  Station. 

in  California.  The  work  of  the  Forestry  Station  under  the  present 
management  has,  therefore,  resolved  itself  almost  entirely  into  a  study 
of  specific  subjects,  beginning  with  that  of  eucalyptus-growing  in 
California,  based  largely  on  field  observations  all  over  the  State  where 
the  trees  are  grown.  This  work  has  been  done  by  Mr.  Ingham,  making 
the  Station  at  Santa  Monica  his  headquarters,  and  utilizing  the  col- 
lection of  trees  there  as  stated  above.  It  is  desirable  that  this  collection 
should  be  duplicated  in  other  places  to  provide  against  its  loss  or  partial 
destruction  from  any  cause,  and  for  this  reason  trees  of  all  the  species 
represented  are  being  grown  with  the  idea  of  finding  opportunities 
for  planting  duplicate  collections  on  public  grounds  in  California. 

PEAR  BLIGHT  WORK. 

This  work,  which  has  been  carried  on  in  co-operation  with  the 
United  States  Department  of  Agriculture,  was  reported  on  at  length 
for  the  first  year  in  our  last  report.  The  detailed  history  and  char- 
acter of  the  undertaking  may  be  obtained  from  that  publication.  The 
second  year's  experience  in  the  work,  the  period  from  July,  1906  to 
July,  1907,  was  in  most  respects  similar  to  that  of  the  first  year  already 


Bulletin  203.  report  OF  PLANT  PATHOLOGIST.  19 

reported  on.  The  work  consisted  in  general  of  an  effort  on  the  part 
of  a  considerable  force  of  field  experts  to  encourage  the  eradication  of 
pear  blight,  according  to  the  methods  established  by  Mr.  M.  B.  Waite 
of  the  Federal  Department  of  Agriculture.  The  working  force 
in  the  field  consisted  of  Messrs.  Waite  and  Scott  of  the  United 
States  Department  of  Agriculture,  with  several  assistants,  six  rep- 
resentatives of  this  Division  of  the  State  Experiment  Station  and 
a  number  of  men  working  under  various  County  Boards  of  Horticul- 
ture. The  plan  of  work  was  largely  that  mentioned  on  page  232  of 
the  last  report.  This  consisted  in  distributing  the  available  men  in 
a  somewhat  permanent  manner  among  the  various  pear-growing  dis- 
tricts, allowing  the  men  in  each  district  to  render  all  possible  assist- 
ance to  the  growers  in  that  part  of  the  State.  No  effort  was  made  on 
the  part  of  the  Experiment  Station  to  enforce  compulsory  eradication. 
The  latter  undertaking  was  left  to  the  discretion  of  the  County  Boards 
of  Horticulture,  the  Station  men  endeavoring  to  give  all  assistance  of 
any  sort  which  was  desired  by  the  growers  in  enabling  them  to  sup- 
press the  disease.  This  work  was  continued  through  the  winter  and 
up  to  July,  1907,  at  which  time  the  appropriation  period  ended  and, 
no  new  funds  being  forthcoming,  the  work  was  obliged  to  lapse. 

The  general  results  of  this  two  years'  work  on  pear  blight  by  the 
Station,  cooperated  in  by  the  United  States  Department  of  Agricul- 
ture and  the  State  and  County  Boards  of  Horticulture,  have  been  by 
no  means  meagre  or  unsatisfactory.  With  the  appropriation  of  $10,000 
made  by  the  legislature  of  1905,  a  force  of  men,  varying  from  six  to 
twelve,  was  kept  in  the  field  for  two  years  in  continual  earnest  work ; 
every  pear  grower  in  those  sections  of  the  State  which  are  largely  in- 
terested in  this  crop  was  visited  many  times  and  thoroughly  instructed 
in  the  best  known  methods  of  handling  the  disease ;  750,000  pear  trees 
were  carefully  inspected  several  times ;  numerous  meetings  and  demon- 
strations were  held  to  promote  the  objects  of  the  work ;  and  in  general 
it  can  fairly  be  said  that  to  the  extent  of  practical  possibility  every- 
thing was  done  to  suppress  this  destructive  disease.  Full  credit  should 
be  given  to  the  other  agencies  mentioned  outside  of  the  Experiment 
Station  for  their  part  in  the  undertaking.  It  is  difficult  to  see  what 
further  could  be  done  under  present  conditions  and  in  the  light  of 
present  knowledge,  but  the  work  has  emphasized  the  necessity  of 
changed  methods  and  increased  knowledge  in  certain  respects.  Along 
such  lines  appears  to  be  the  greatest  hope  for  the  future  of  the  pear 
industry  in  California.  After  the  amount  of  work  done  in  the  field 
by  the  agents  of  the  Experiment  Station  and  Department  of  Agricul- 
ture it  does  not  appear  to  the  writer  probable  that  further  work  of 


20 


UNIVERSITY  OF  CALIFORNIA EXPERIMENT  STATION. 


Fig.  5. — Bartlett  pear  tree  on  ordinary  root,  showing  mass  of  suckers. 


Bulletin  203.  REPORT  OF  PLANT  PATHOLOGIST.  21 

this  sort  on  a  large  scale  could  be  of  much  profit.  Our  pear  growers 
have  had  every  opportunity  to  become  thoroughly  informed  as  to 
the  methods  of  control  advocated  and  to  put  them  into  practice.  So 
far  as  these  methods  are  applicable  to  existing  conditions  there  should 
be  no  further  necessity  for  their  demonstration.  Pear  blight,  how- 
ever, has  by  no  means  been  eradicated  from  California,  nor  is  it 
likely  to  be.  The  future  of  the  industry  is  therefore  still  problemat- 
ical, although  a  considerable  number  of  individual  growers  are  hand- 
ling blight  successfully. 

One  of  the  most  valuable  results  obtained  from  the  work  done 
thus  far  has  been  the  experience  gained  as  to  the  behavior  of  the  dis- 
ease under  California  conditions.  Of  these  peculiarities  there  are 
two  which  seem  of  particular  importance,  since  they  are  the  factors 
which  have  most  largely  prevented  complete  control  of  pear  blight 
in  California ;  these  are :  first,  the  very  large  amount  of  infection  of 
twigs  and  green  shoots  which  occurs  with  no  relation  to  the  blossoms ; 
second,  the  large  number  of  trees  which  become  infected  in  the  body 
near  the  ground  or  in  the  butt  under  ground.  In  the  latter  case  the 
blight  runs  down  into  the  roots  and  often  girdles  and  kills  trees  which, 
in  the  tops,  appear  perfectly  healthy,  or  only  slightly  affected  with 
the  disease.  So  far  as  the  usual  form  of  the  disease  is  concerned, 
occurring  in  the  top  of  the  tree  with  the  infection  mostly  through 
the  blossoms,  our  growers  have  learned  to  handle  it  with  considerable 
success  by  the  usual  methods  where  the  work  is  done  carefully. 

The  one  most  discouraging  and  baffling  feature  of  the  disease  has 
been  that  mentioned,  where  large  numbers  of  trees  in  an  orchard  ap- 
parently free  from  blight  would  suddenly  be  found  affected  in  the 
butts  and  thus  beyond  redemption  by  the  methods  of  handling  blight 
in  the  tops.  Could  this  difficulty  be  overcome  we  believe  that  pear 
growing  would  again  flourish  on  a  sound  basis,  though  requiring  more 
care  and  attention  than  at  present. 

During  the  years  1907-09  our  chief  activity  in  regard  to  pear 
blight  has  been  along  the  line  suggested  in  the  last  paragraph,  car- 
ried on  under  the  provisions  of  the  Adams  Act.  This  work  has 
consisted  mostly  in  an  effort  to  determine  the  method  by  which  in- 
fection takes  place  in  cases  where  the  green  twigs  and  shoots  contract 
the  disease  so  abundantly,  and  also  to  investigate  the  possibility  of 
growing  trees  in  such  a  way  as  to  avoid  the  butt  blight  mentioned 
above.  It  has  been  found  that  the  latter  form  of  the  disease  is  a  result 
of  the  other  peculiarity  mentioned,  the  infection  of  the  butts  taking 
place  through  green  sprouts  or  suckers,  sometimes  when  the  latter 
amount  to  no  more  than  a  bud  with  onlv  one  or  two  leaves  formed  in 


22 


UNIVERSITY  OF   CALIFORNIA EXPERIMENT   STATION. 


Fig.  6 — Bartlett  top — worked  on  LeConte.     Neighboring  trees  on  ordinary 
root  are  four  years  older  but  considerably  smaller. 


Bulletin  203.  REPORT  OF  PLANT  PATHOLOGIST.  2'4 

the  rough  bark  near  the  butt.  Infection  of  this  sort  appears  to  be 
brought  about  in  a  similar  manner  to  that  in  blossom  infection,  mainly 
by  insects.  Our  investigations  have  shown  that  a  great  variety  of 
insects  which  feed  on  the  green  shoots  may  carry  the  blight  organism 
and  thus  produce  infection.  There  is  no  apparent  means  of  prevent- 
ing this  form  of  the  disease  beyond  that  which  has  already  been  in 
use,  namely,  the  removal  of  sprouts  from  the  body  of  the  tree,  and 
this  has  not  proven  very  satisfactory  on  account  of  the  continual 
crop  of  suckers  produced  by  many  trees,  some  of  which  become  in- 
fected while  still  very  small.  There  is  also  some  infection  through 
wounds  made  by  cutting  off  the  suckers. 

The  most  promise  is  in  the  direction  of  growing  trees  upon  a  stock 
more  or  less  immune,  or  one  which  is  not  disposed  to  produce  sprouts, 
thus  avoiding  the  infection  of  the  trees  by  blight  in  the  trunk  or 
roots.  It  is  well  known  that  different  varieties  of  trees  vary  in  their 
susceptibility  to  blight.  None  are  entirely  immune  under  all  condi- 
tions, but  some  are  much  more  so  than  others. 

The  whole  consideration  of  pear  blight  in  California  rests  pri- 
marily upon  the  fact  that  the  word  "pear"  in  this  State  means  or- 
dinarily the  Bartlett  pear.  This  variety  is  so  preeminently  satisfac- 
tory that  while  it  is  one  of  the  most  susceptible  to  blight  and  other 
varieties  much  less  affected  are  to  be  found,  yet  the  giving  up  of 
the  Bartlett  pear  would  mean  practically  the  giving  up  of  the  pear 
industry.  The  development  of  a  new  variety  as  satisfactory  as  the 
Bartlett,  but  fairly  resistant  to  the  blight,  would  be  a  most  uncertain 
undertaking.  Our  chief  thought  has,  therefore,  been  as  to  the  pos- 
sibilities of  growing  the  Bartlett  under  some  system  by  which  the 
tree  could  be  rendered  less  susceptible  to  destruction.  The  ordinary 
French  seedling  root  upon  which  pear  trees  are  commonly  grown 
has  two  vital  defects  in  relation  to  blight.  It  is  very  free  to  sucker 
and  it  is  very  susceptible  to  the  disease.  These  suckers  become  in- 
fected, the  blight  runs  down  into  the  butt  and  roots,  and  the  tree 
is  killed  while  the  top  is  still  in  good  condition.  The  Bartlett  pear 
tree  trunk  also  suckers  rather  freely  and  blights  readily.  It  there- 
fore seems  that  it  would  be  of  great  practical  advantage  if  the  Bart- 
lett could  be  grown  on  a  trunk  and  root  somewhat  resistant  to  blight 
and  not  given  to  sending  up  suckers.  With  a  Bartlett  top  worked 
on  this  combination  an  orchard  could  certainly  be  kept  free  from 
serious  injury  much  more  readily  than  with  the  present  style  of  tree. 

The  extensive  experience  gained  in  our  work  on  pear  blight  has 
shown  among  the  trees  now  growing  in  the  State  one  suggestion  of 
particular  value.     This  is  the  growing  of  the  Bartlett  upon  rooted 


24  UNIVERSITY  OF  CALIFORNIA EXPERIMENT  STATION. 

cuttings  of  the  LeConte.  The  latter  variety  while  by  no  means 
blight-proof,  is  much  less  easily  affected  than  the  Bartlett.  It  roots 
readily  from  cuttings  and  produces  a  trunk  decidedly  free  from  suck- 
ers. Trees  of  this  combination  existing  in  the  State  have  shown  a 
most  vigorous  growth,  considerably  exceeding  that  of  the  Bartlett 
on  the  ordinary  root.  It  should  be  clearly  understood  that  there  is 
no  idea  that  the  Bartlett  top  would  gain  any  immunity  from  blight 
from  growing  on  the  LeConte.  The  sole  object  is  simply  to  grow 
the  root  and  trunk  free  from  the  disease  and  confine  the  blight  to 
the  top  of  the  tree,  where  it  can  be  more  readily  seen  and  handled, 
and  where  its  effects  are  less  disastrous.  As  to  the  growth  of  the  Bart- 
lett on  the  LeConte,  what  experience  we  can  gather  goes  to  show 
that  the  tree  thus  grown,  while  unusually  thrifty  and  vigorous,  is 
very  slow  in  coming  into  bearing.  This  has  been  learned  particu- 
larly from  Mr.  Richard  Burton,  of  Vacaville,  who  has  old  trees  of 
this  sort  and  whose  experience  forms  the  basis  of  most  of  what  is 
said  upon  this  subject,  It  has  therefore  been  suggested  that  the  trees 
be  double  worked,  with  some  other  variety  between  the  LeConte  root 
and  the  Bartlett  top,  in  order  to  promote  early  bearing.  The  Hardy 
suggests  itself  as  one  possibility  for  this  purpose,  as  it  succeeds  well 
in  California  and  has  shown  itself  to  be  quite  free  from  blight.  For 
the  purpose  of  a  thorough  investigation  and  demonstration  along  these 
lines  pear  trees  are  being  grown  by  this  Division,  trying  out  various 
combinations  as  to  root  and  trunk,  along  the  lines  suggested.  The 
results  already  obtained  give  considerable  promise  of  success.  Our 
main  object  will  be  to  demonstrate  the  possibility  of  growing  a  nurs- 
ery tree  with  a  Bartlett  top  which  can  be  planted  in  the  orchard  and 
kept  free  from  blight  simply  by  keeping  the  disease  out  of  the  top. 

The  seasons  of  1908  and  1909  have  been  most  remarkable  in  the 
absence  of  pear  blight  throughout  the  affected  districts.  The  disease 
has  disappeared  in  an  astonishing  manner  where  for  the  last  few 
years  it  has  been  most  abundant.  This  freedom  from  blight  is  evi- 
dently a  climatic  effect  and  is  encouraging  in  showing  the  possibility 
of  occasional  years  of  little  blight  when  a  tree  may  have  an  oppor- 
tunity for  recovery,  but  should  not  be  taken  as  indicating  a  perma- 
nent cessation  of  pear  blight. 

WALNUT  BLIGHT  AND  CULTURE. 

A  large  amount  of  work  on  walnut  blight  has  been  carried  on  in 
southern  California  at  the  Whittier  Laboratory,  and  still  continues. 
The  appropriation  of  $4,000  made  by  the  1905  legislature  was  ex- 
pended in  an  investigation  of  the  nature  of  the  disease  and  the  pos- 


Bulletin  203. 


REPORT  OF  PLANT  PATHOLOGIST. 


25 


Fig.    7. — Specimens   of   blight-immune    walnuts.      A    Franquette, 

B  Mayette,  C  Eureka,  D   San  Jose    (Wiltz'   Mayette 

Seedling),  E  Hale,  F  Placentia  (not  immune). 

Natural  size. 


26  UNIVERSITY  OF  CALIFORNIA EXPERIMENT  STATION. 

sibility  of  its  control  by  spraying  the  trees  with  different  substances. 
This  investigation  has  been  made  one  of  the  chief  features  of  the 
work  of  the  Southern  Laboratory  since  its  establishment.  From  the 
experience  previously  gained,  the  idea  of  finding  a  remedy  for  the 
disease  in  the  form  of  any  application  to  the  tree  has  been  given  up 
as  impractical,  and  the  chief  effort  is  now  being  made  along  the  lines 
of  improved  cultural  practice,  thus  increasing  the  production  of  the 
trees. 

The  greatest  possibilities  in  this  direction  seem  to  lie  in  soil  fer- 
tilization, and  extensive  experiments  along  such  lines  are  being  carried 
on  by  this  Division.  Some  of  these  are  now  in  their  third  season 
and  ought  to  show  results  in  the  crop  of  1909.  It  is  already  very 
evident  that  in  spite  of  the  disease  the  production  of  most  of  the 
present  orchards  could  be  greatly  increased  by  fertilizing  the  soil, 
if  the  most  economical  method  in  this  respect  was  determined.  In 
regard  to  irrigation,  also,  as  affecting  the  condition  of  the  trees,  con- 
siderable benefit  is  being  demonstrated  by  the  determination  of  the 
best  practice  in  this  regard. 

The  ultimate  solution  of  the  blight  problem  appears  to  be  in  the 
growing  of  walnuts  immune  to  the  blight,  desirable  types  of  which 
are  already  in  existence.  Much  work  is  being  done  at  the  Whittier 
Laboratory  in  this  direction.  This  involves  the  growing  of  grafted 
rather  than  seedling  trees  and  thus  opportunity  is  given  for  choice 
regarding  both  the  root  and  the  top  of  the  tree.  Each  is  of  great 
importance.  Extensive  plantings  have  been  made  at  the  Laboratory  of 
nuts  of  various  kinds  and  sources  for  the  production  of  root  stocks. 
These  represent  several  species  of  walnuts  and  also  hybrids  be- 
tween different  species.  Experience  has  already  shown  that  in 
the  native  California  black  walnut  we  have  a  more  hardy  root 
than  that  of  the  English  walnut,  one  that  is  more  capable  of  flour- 
ishing under  unfavorable  conditions  and  one  with  a  much  wider 
range  of  soil.  The  native  walnut  varies,  however,  in  individual  trees 
almost  as  much  as  the  cultivated  species,  so  that  there  is  room  for 
careful  selection  and  discrimination  in  growing  a  root  stock.  The 
California  walnut  is  also  divided  more  or  less  distinctly  into  two 
separate  species.  It  may  be  classed  as  the  southern  California  and 
northern  California  types.  The  tree  which  grows  wild  in  the  south- 
ern part  of  the  State  has  its  favorite  habitat  upon  dry,  somewhat 
elevated  hillsides  with  occasional  trees  in  the  valleys  at  the  foot  of 
these  hills.  It  is  distinctly  a  hillside  rather  than  a  valley  tree,  how- 
ever. The  tree  itself  has  quite  a  shrubby  rather  than  a  tree-like 
form  and,  even  in  large  specimens  grown  on  good  soil  with  abundant 


Bulletin  203. 


REPORT  OF  PLANT  PATHOLOGIST. 


27 


water,  the  tendency  is  still  towards  abundant  branching  rather  than 
the  formation  of  a  tall,  clean  trunk.  The  nut  of  this  type  is  a  very 
small  one.  According  to  the  latest  arrangement  by  Professor  W.  L. 
Jepson,  the  southern  California  walnut  is  to  be  regarded  as  Juglans 
californica  Wats.  It  grows  quite  abundantly  in  the  Puente  hills 
southeast  of  Whittier  and  in  the  Santa  Monica,  Newhall  and  other 
mountains  of  that  vicinity,  extending  north  at  least  to  the  Ojai  val- 
ley back  of  Ventura.  This  species  is  also  found  to  some  extent  in 
the  lower  parts  of  the  San  Bernardino  range. 


Fig.  8. — Two  blight-immune  walnuts:    A  Concord,  B  Chase.     Natural  size. 


The  northern  California  nut  averages  fully  twice  as  large,  and 
the  tree  has  typically  a  tall  regular  form  approaching  that  of  the 
eastern  black  walnut.  This  is  classed  by  Dr.  Jepson  as  Juglans  hindsii 
Jepson.  The  origin  of  the  northern  California  walnut  is  much  in 
doubt.  While  this  tree  is  one  of  the  commonest  grown  for  shade  and 
ornament  about  many  of  the  towns  in  central  and  northern  Califor- 
nia, yet  there  are  only  a  very  few  places  where  there  is  any  indica- 
tion of  the  tree  having  been  indigenous.  Considerable  attention  has 
been  given  to  this  interesting  question  and  we  have  found  but  three 
locations  where  the  walnut  trees  go  back  beyond  the  knowledge  of 
any  white  person.  These  are :  1,  near  Walnut  Creek,  Contra  Costa 
County;  2,  Walnut  Grove,  Sacramento  County;  3,  a  point  in  the 
mountains  of  Napa  County,  northeast  of  Napa  City,  near  the  top 
of  the  west  slope  of  the  so-called  ' '  Wooden  Valley. ' '    In  each  of  these 


28 


UNIVERSITY  OF  CALIFORNIA EXPERIMENT  STATION. 


Fig.  9. — Walnuts    used    for    root-stocks.      A    Northern    California    Black 

(Juglans   hindsii),   B   Eastern   or   American  Black    (J.   nigra), 

C  Southern  California  Black  (J.  calif ornica),  D  Hybrid 

English    X    calif  ornica,    E    Hybrid,    nigra    X 

calif  ornica. 


Bulletin  203. 


REPORT  OF  PLANT  PATHOLOGIST. 


29 


places,  and  at  no  other  which  we  can  find,  there  were  large  old  black 
walnut  trees  growing  at  the  time  of  the  first  white  settlement.  These 
primeval  trees  do  not  appear  to  have  been  indigenous  to  the  localities 
where  they  are  found,  but  the  question  of  their  origin  is  an  extremely 
obscure  one.  Morphological  and  field  studies  are  being  made  by  Mr. 
Ramsey  upon  this  subject.  The  northern  tree  shows  a  decided  pref- 
erence for  a  moist  valley  soil  in  the  vicinity  of  streams  rather  than 
that  of  the  south  for  growing  on  dry  hillsides. 

Both  the  northern  and  southern   California  walnuts  have  been 
found  satisfactory  as  a  root  stock  for  the  English,  but  we  have  as 


Fig.  10.— Top-grafted  walnut  trees,  March,  1908. 


yet  no  sufficient  comparison  between  them  to  judge  finally  as  to 
which  is  the  better.  Such  comparisons  are  now  being  made  by  this 
Division  by  grafting  English  walnuts  on  various  roots  and  planting 
them  in  various  soils.  The  possibility  of  using  for  roots  some  of 
the  not  uncommon  hybrids  between  the  California  black,  American 
black  and  English  walnuts  is  also  receiving  much  attention,  on  ac- 
count of  the  extremely  vigorous  growth  of  these  trees.  Selected 
walnuts  from  all  over  the  State  as  well  as  from  other  parts  of  the 
country  have  been  planted  at  Whittier,  and  a  very  interesting  nurs- 
ery is  in  process  of  development. 

The  selection  of  a  strain  or  variety  of  English  walnut  possessing 
immunity  to  the  blight  as  well  as  desirable  commercial  qualities  is 
receiving  much  attention.     Immunity  to  this  disease  is  not  obtained 


30 


UNIVERSITY  OF  CALIFORNIA. — EXPERIMENT  STATION. 


entirely  by  actual  resistance,  but  in  many  cases  by  simply  escaping 
the  worst  infection  period:  i.e.,  the  moist  weather  of  early  spring. 
Most  of  the  immune  trees  are  such  as  come  out  rather  late  in  the 
spring,  thus  escaping  rather  than  resisting  the  blight.  Several  of 
the  ordinary  French  walnuts,  such  as  the  Franquette  and  Mayette, 
have  this  quality  of  lateness  in  an  extreme  degree,  but  this  involves 


Fig.  11. — Same  trees  as  in  figure  9;  July,  1908. 


the  question  of  the  time  of  harvest  in  the  fall,  an  extremely  late  crop 
not  being  desirable  in  California.  The  most  promising  trees  found 
thus  far  are  local  seedlings  of  foreign  varieties  which  develop  some- 
what later  than  our  ordinary  seedlings,  but  not  so  late  as  the  French 
varieties  mentioned.  A  number  have  been  found  which  seem  to  jus- 
tify their  planting  as  blight-immune.  Among  these  we  may  men- 
tion varieties  which  have  received  the  names  Eureka,  Concord,  Chase, 
and   San  Jose,   as  well  as  the  Franquette   and  Mayette  mentioned 


Bulletin  203. 


REPORT  OF  PLANT  PATHOLOGIST. 


31 


above.  All  of  these  and  many  other  varieties  are  being  grown  by 
this  Division  and  their  value  carefully  tested  for  various  portions  of 
the  State.  We  are  now  in  a  position  to  supply  scions  of  all  the  im- 
portant walnut  varieties,  as  well  as  a  limited  number  of  nursery 
trees  of  some. 


Fig.  12. — English  walnut  grafted  on  California  black. 

One  very  imperative  phase  of  this  matter  has  been  the  question 
as  to  the  fate  of  the  present  existing  plantings,  consisting  of  many 
thousand  acres  of  fine,  large,  thrifty  trees,  very  satisfactory  in  every 
way  except  for  the  occasional  loss  of  a  considerable  part  of  the  crop 
through  their  susceptibility  to  the  disease.  Many  of  these  orchards 
are  extremely  profitable,   even  under  present   conditions,    and   it   is 


32  UNIVERSITY  OF  CALIFORNIA EXPERIMENT  STATION. 

evident  that  by  increased  attention  to  soil  fertilization  their  produc- 
tiveness can  be  maintained  in  a  very  satisfactory  degree  in  spite  of 
the  disease. 

One  means  of  handling  large  trees  which  are  extremely  suscep- 
tible to  blight  is  by  top  grafting  them  to  the  more  immune  kinds. 
The  methods  of  doing  this  have  received  the  consideration  of  this 
Division,  and  much  work  has  been  done  along  this  line.  During  1908 
and  1909  a  considerable  number  of  large  trees  were  top  grafted,  both 
by  the  Station  and  by  individual  growers,  with  decided  success.  Ex- 
perience elsewhere,  particularly  in  the  central  part  of  the  State, 
where  many  large  native  walnuts  have  been  grafted  to  the  English 
variety,  has  shown  that  with  reasonable  success  a  new  top  equal  to 
the  original  one  can  be  put  on  a  large  tree  in  four  years.  In  orchard 
work  the  most  rational  practice  appears  to  be  the  picking  out  and 
working  over  of  the  trees  most  susceptible  to  blight  each  year  until 
finally  the  whole  orchard  has  been  changed.  In  this  way  there  is 
no  marked  loss  from  cutting  off  the  trees  in  any  one  season. 

Another  method  of  working  over  an  old  orchard  consists  in  inter- 
setting  with  nursery  trees  of  the  California  black  walnut.  It  is 
more  practical  to  plant  the  young  trees  rather  than  the  nuts  in  the 
orchard.  The  object  of  this  method  is  to  grow  the  black  walnut 
trees  up  to  three  or  four  years  old  and  then  graft  them  in  the  top 
to  the  desired  variety.  If  the  ground  is  closely  shaded  by  old  trees 
they  should  be  thinned  enough  to  give  the  young  black  walnuts  a 
chance  to  grow.  This  thinning  can  be  done  in  most  of  our  older 
orchards  without  any  disadvantage,  as  in  most  of  them  the  trees 
are  already  too  thick.  The  young  grafted  trees  will  come  into  bear- 
ing early,  and  it  is  possible  by  this  plan  to  have  a  new  orchard  well 
started  by  the  time  it  is  necessary  to  cut  out  the  old  trees.  The 
advantage  of  a  tree  having  the  black  walnut  trunk  as  well  as  root 
is  a  very  considerable  one,  owing  to  the  susceptibility  of  the  English 
walnut  trunk  to  sunburn. 

The  publication  of  a  bulletin  on  walnut  blight  and  walnut  culture 
in  general  is  contemplated  for  the  present  year. 

LEMON   ROT    INVESTIGATION. 

The  investigation  of  the  form  of  lemon  decay  known  as  "Brown 
Rot",  which  was  begun  in  July  1905,  was  practically  completed  dur- 
ing the  year  1906-7  and  reported  on  in  full  in  Bulletin  No.  190.  Suc- 
cessful means  of  preventing  the  great  losses  which  had  occurred  from 
this  trouble  were  found  and  a  detailed  account  of  the  whole  subject 
may  be  found  in  the  bulletin  mentioned.     This  work  has  led  to  fur- 


Bulletin  203.  REPORT  OF  PLANT  PATHOLOGIST.  33 

ther  investigations  upon  lemon  decay  and  other  phases  of  the  lemon 
business  at  the  Whittier  Laboratory. 

SUGAR-BEET    BLIGHT    INVESTIGATION. 

The  blight  or  curly  top  of  the  sugar-beet  has  been  a  subject  of 
investigation  in  this  Division  for  some  time,  as  mentioned  in  our 
last  report.  This  work  has  been  in  cooperation  with  the  Spreckels 
Sugar  Company  and  other  beet  growers  of  the  State,  continuing  dur- 
ing the  period  from  the  spring  of  1905  to  the  fall  of  1906.  In  1907 
the  company  mentioned  took  two  of  our  assistants  into  its  own  em- 
ploy and  has  since  then  continued  the  field  work  through  them. 

Some  investigations  of  a  technical  nature  are  being  carried  on  in 
relation  to  the  nature  of  this  disease  at  the  Whittier  Laboratory. 
From  the  work  thus  far  it  appears  to  be  well  established  that  the 
trouble  is  largely  influenced  by  meteorological  factors  varying  from 
one  season  to  another. 

PEACH  BLIGHT   INVESTIGATION. 

Active  work  on  this  subject  was  completed  in  the  winter  of  1906-7 
and  a  bulletin  on  the  subject  (Bulletin  No.  191)  published  in  Sep- 
tember, 1907.  Work  during  the  year  mentioned  consisted  mostly  in 
extensive  field  work  and  demonstrations,  having  for  their  object  a 
general  application  of  the  method  of  treatment  found  successful  in 
previous  years.  This  work  came  to  a  very  successful  conclusion,  as 
described  in  the  bulletin  mentioned. 

ROSE   DISEASE    INVESTIGATION. 

Owing  to  the  delay  in  publication  of  a  bulletin  on  this  subject, 
which  was  promised  in  our  last  report,  it  has  been  possible  to  gather 
other  data  to  supplement  that  previously  obtained.  During  the  past 
two  seasons  a  thorough  survey  has  been  made  of  the  various  varieties 
of  roses  growing  in  most  of  the  important  nurseries  in  the  State, 
as  well  as  on  private  grounds,  in  order  to  determine  the  relative 
degree  of  susceptibility  of  the  various  varieties  to  the  usual  rose 
diseases. 

Further  work  on  the  treatment  of  the  rose  mildew  has  also  been 
carried  out  on  a  considerable  scale  during  the  past  season. 

APRICOT  DISEASE  INVESTIGATION. 

Work  on  this  subjoct  has  been  carried  on  for  some  time  in  con- 
nection with  the  peach  blight  work  and  has  received  special  attention 
during  the  years  1907-09.     The  main  object  has  been  to  determine 


34 


UNIVERSITY  OF  CALIFORNIA — EXPERIMENT  STATION. 


Fig.  13.— Apricot  buds  killed  by  peach  blight  fungus,  Coryneum 

beyerinlcii. 


Bulletin  203.  REPORT  OF  PLANT  PATHOLOGIST.  35 

the  nature  of  the  trouble  with  apricots  which  so  reduced  the  crop 
in  the  State  for  several  years  previous  to  1908  and  to  determine  the 
extent  to  which  the  apricot  is  being  affected  by  the  peach  blight 
fungus,  Cory neum  beyerinkii. 

We  are  convinced  that  the  death  of  the  fruit  buds  of  the  apricot 
previous  to  blooming  which  has  been  so  prevalent  in  many  localities, 
may  be  due  to  the  fungus  just  mentioned,  and  that  a  spotting  of  the 
leaves  and  fruit  at  an  early  stage  is  also  caused  by  Coryneum.  This 
spot  is  quite  characteristic,  usually  less  than  a  millimeter  in  diam- 
eter, red,  with  light  centre.  It  is  distinct  in  appearance  from  any 
other  apricot  spot  which  has  come  under  our  observation,  but  might 


Fig.  14. — Black  spot  of  apricot  fruit,  caused  by  Cladosporium. 

easily  be  confused  with  a  seemingly  physiological  effect  which  is  very 
general.  This  is  a  reddish  dot,  smaller  even  than  the  Coryneum  spot 
and  less  definite  in  outline,  which  at  its  minimum  is  nearly  always 
present,  and  might  almost  be  called  a  normal  condition  of  the  fruit. 
Its  cause  is  not  yet  understood,  but  it  does  not  appear  to  be  a  para- 
sitic disease.  It  is  quite  possible  that  this  is  the  "apricot  scab" 
which  is  claimed  to  have  been  prevalent  in  the  State  many  years 
before  the  Coryneum  blighting  of  the  buds  began.  This  can  only  be 
determined  by  observation  of  the  fruit  during  "off  years"  for  Cory- 
neum blight  for  a  number  of  seasons.  Such  was  the  year  just  past, 
and  so  far  as  the  writer  has  been  able  to  observe  there  has  been  com- 
paratively little  spotting  of  the  fruit  in  most  sections.     What  has 


36 


UNIVERSITY  OF  CALIFORNIA EXPERIMENT  STATION. 


Fig.  15. — Apricot  "Scab"  and  "Shot  hole." 


Bulletin  203.  report  of  plant  pathologist.  37 

come  under  our  observation  may  be  classed  under  three  heads :  Cory- 
neum spotting  (very  slight),  the  physiological  effect  (rather  more 
than  the  Coryneum),  and  a  black  spot  of  apricot,  which  has  been 
rather  prevalent  in  some  sections. 

The  black  spot  was  first  sent  us  for  identification  by  Mr.  Earl 
Morris,  Entomologist  for  Santa  Clara  County.  It  is  caused  by  a 
fungus,  Cladosporium  carpophilum,  described  by  von  Thumen  and 
since  reported  by  Arthur,  Smith,  and  others  as  damaging  peaches 
and  plums.  The  fuugus  forms  a  thin,  black  coating  in  spots  about 
2-3  mm.  in  diameter  when  isolated,  which  causes  the  fruit  to  dry  and 
crack,  especially  when  the  spots  are  confluent.  It  attacks  the  fruit 
later  in  the  season,  and  is  in  every  way  distinct  from  the  Coryneum 
spot. 

The  uncertainty  of  the  apricot  crop  during  recent  seasons  and 
its  susceptibility  to  climatic  conditions  has  rendered  difficult  the 
determination  of  the  actual  causes  of  these  troubles.  From  experi- 
ence thus  far  it  appears  that  the  Coryneum  treatment  recommended 
for  peaches,  in  Bulletin  No.  191,  consisting  of  two  sprayings  with 
Bordeaux  mixture,  one  in  November  and  the  other  in  February,  will 
prove  as  effective  with  apricots  as  with  peaches. 


OLIVE   KNOT    INVESTIGATION. 

The  knot  or  Tuberculosis  of  the  Olive  has  been  known  in  the 
State  for  several  years,  but  until  a  comparatively  recent  period  did 
not  seem  to  assume  a  very  serious  aspect.  Bulletin  No.  120  of  this 
Station  was  published  several  years  ago  on  the  subject,  describing 
the  disease  quite  fully.  In  some  sections  the  trouble  has  now  devel- 
oped to  such  an  extent  as  to  make  its  control  seem  quite  necessary 
for  the  future  of  the  industry,  so  many  trees  having  become  badly 
affected.  On  this  account  cooperative  arrangements  were  made  dur- 
ing 1908  with  olive  growers  in  certain  sections  where  the  disease  is 
most  troublesome  and  investigations  started  in  an  effort  to  obtain 
further  information  concerning  this  trouble.  It  seemed  particularly 
desirable  to  learn  the  method  and  source  of  infection  in  the  olive  knot 
disease  concerning  which  we  have  hitherto  had  no  information.  This 
work  was  carried  on  during  the  summer  of  1908  by  Professor  Bab- 
cock  and  Mr.  W.  B.  Parker  and  will  continue  to  receive  attention. 
It  is  highly  probable  that  a  definite  mode  of  infection  wall  be  found 
which  may  give  an  important  clue  to  possible  means  of  control. 


38 


UNIVERSITY  OF  CALIFORNIA EXPERIMENT   STATION. 


Fig.  16. — Olive  knot. 


Bulletin  203. 


REPORT  OF  PLANT  PATHOLOGIST. 


39 


ONION  MILDEW  INVESTIGATION. 

The  growing  of  onions  for  seed  is  a  large  industry  in  California. 
In  connection  with  this  business  much  trouble  has  been  experienced 
for  a  number  of  years  on  account  of  the  attacks  of  a  fungous  disease, 
the  Downy  Mildew  of  the  Onion  (Peronospora  schleideniana) .  This 
fungus  makes  its  attack  on  the  leaves  and  seed  stalks  of  the  plant  dur- 
ing moist  weather,  causing  large  losses  in  the  crop.  Its  occurrence 
varies  from  year  to  year  on  account  of  climatic  conditions,  and  for 
this  reason  we  have  never  been  able  to  secure  satisfactory  demonstra- 
tions as  to  the  possibility  of  controlling  the  trouble  by  spraying.  Dur- 
ing the  season  of  1908  spraying  experiments  were  arranged  by  this 
Division  more  extensively  than  ever  before  with  the  hope  of  finding 
a  practical  treatment  for  controlling  the  trouble.  The  season  was 
not  a  favorable  one  for  the  disease,  however,  so  that  the  results  se- 
cured have  not  been  satisfactory. 


Fig.  17. — Brown  rot  of  plum.     (Sclerotina.) 


BROWN  EOT  OF  STONE  FRUITS  INVESTIGATION. 

What  has  been  said  of  the  preceding  subject  applies  equally  well 
to  the  present  one.  This  fungus  (Sclerotinia  fructigena),  which 
causes  a  very  destructive  decay  of  peaches,  plums,  apricots,  etc.,  when 
conditions  are  favorable,  varies  in  its  occurrence  in  this  State  with 
the  character  of  the  season  as  to  moisture.  The  trouble  has  never 
become  general  over  the  State,  but  in  seasons  with  late  spring  rains 
has  been  very  troublesome  in  the  San  Francisco  Bay  region  on  early 


40  UNIVERSITY  OF  CALIFORNIA EXPERIMENT  STATION. 

peaches,  apricots  and  certain  varieties  of  plums.  During  1908  ar- 
rangements were  made  for  careful  spraying  demonstrations  at  a  num- 
ber of  points  in  the  affected  region,  and  the  Division  was  prepared 
to  give  the  matter  thorough  attention.  On  account  of  the  dry  season, 
however,  there  was  practically  no  occurrence  of  the  trouble.  It  ap- 
pears probable  that  in  seasons  with  late  rain  a  spraying  with  any 
standard  fungicide  not  injurious  to  the  foliage,  directly  following 
each  rain  after  the  crop  is  set,  would  control  this  trouble  quite  effec- 
tively. In  the  case  of  brief  showers  followed  by  drying  weather,  the 
brown  rot  is  not  likely  to  develop  and  spraying  is  not  necessary. 


Fig.  18.— Celery  field,  Smeltzer,  Cal. 


CELERY  BLIGHT  INVESTIGATION. 


Another  important  work  is  that  which  has  been  begun  in  coopera- 
tion with  the  celery  growers  of  the  extensive  Orange  County  district. 
In  the  peat  lands  of  this  section,  located  between  Santa  Ana  and 
the  coast  in  the  vicinity  of  Smeltzer,  a  very  large  celery  growing  in- 
dustry has  developed,  the  crop  being  grown  particularly  for  shipping 
during  the  winter  after  the  eastern  celery  has  had  its  season.  During 
the  summer  of  1907  nearly  6,000  acres  of  celery  were  planted  in  this 
district,     Great  losses  in  the  crop  were  experienced  in  the  winter  of 


Bulletin  203.  REPORT  OF  PLANT  PATHOLOGIST. 


41 


Fig.  19. — Celery  blight,  caused  by  Septoria  petroselini  var  apii. 


42  UNIVERSITY  OF  CALIFORNIA — EXPERIMENT  STATION. 

1908  from  a  fungous  disease  causing  a  blight  of  the  leaves  of  the 
celery  plants  and  heavy  decay  during  shipment.  (Septoria  petrose- 
lini,  var.  apii).  These  losses  were  estimated  as  causing  a  shrinkage 
of  1,950  carloads  in  shipment  and  had  a  most  disastrous  effect  upon 
the  quality  of  the  celery  on  arrival  in  the  eastern  markets  and  the 
financial  returns  from  the  crop.  The  whole  money  loss  of  the  season 
caused  by  this  fungous  disease  was  conservatively  estimated  at 
$550,000.00. 

Spraying  the  plants  in  the  field  with  Bordeaux  mixture  was  tried 
by  a  few  during  this  time  with  decidedly  beneficial  results,  even 
though  not  begun  until  the  disease  had  already  appeared. 

As  a  result  of  this  experience  and  with  the  knowledge  of  the  suc- 
cessful control  of  this  disease  in  other  sections  by  such  spraying, 
the  Orange  County  Celery  Growers'  Association,  which  comprises 
practically  all  the  celery  growers  of  that  section,  made  plans  for  a 
general  spraying  campaign  during  the  season  of  1908-09.  Copper 
sulphate  and  lime  were  purchased  in  large  quantities  by  the  Asso- 
ciation and  practically  every  grower  sprayed  his  fields  faithfully 
and  to  the  best  of  his  ability  throughout  the  season.  The  acreage 
planted  was  much  less  than  that  of  the  year  before,  amounting  to 
only  about  2,700  acres.  The  spraying  thus  carried  on  by  the  vari- 
ous growers  naturally  varied  a  great  deal  in  regard  to  thoroughness 
and  other  details,  but  resulted  in  general  in  a  most  striking  demon- 
stration of  the  value  of  such  work.  In  unsprayed  fields  the  blight 
was  as  bad  or  worse  than  ever  before,  but  as  a  result  of  the  spraying 
done  by  the  members  of  the  Association  the  crop  was  carried  through 
in  excellent  condition,  put  on  the  market  in  the  best  of  shape,  and 
the  financial  returns  were  exceptionally  good.  The  Division  of  Plant 
Pathology  was  able  to  be  of  considerable  assistance  in  the  matter  by 
occasional  inspections  and  the  giving  of  advice  and  instructions  in 
regard  to  the  spraying  operations.  There  is  still  a  large  field  for 
work  in  this  direction  in  perfecting  the  methods  of  preparing  and 
applying  the  spray  to  fit  the  particular  needs  of  the  celery  growers, 
and  also  in  demonstrating  the  most  economical  and  effective  practice 
in  regard  to  time,  frequency  and  other  details  of  spraying.  This 
work  will  be  carried  on  by  the  Division  during  the  coming  season 
on  a  somewhat  more  extensive  basis  than  heretofore,  in  cooperation 
with  the  Celery  Growers  Association,  the  California  Vegetable  Union, 
and  the  Golden  West  Celery  and  Produce  Company. 


Bulletin  203. 


REPORT  OF  PLANT  PATHOLOGIST. 


43 


Fig.  20. — Apple  mildew. 


44  UNIVERSITY  OF  CALIFORNIA EXPERIMENT  STATION. 

APPLE   MILDEW   INVESTIGATION. 

The  powdery  mildew,  one  of  the  worst  troubles  affecting  apples 
in  California,  has  become  abundant  in  all  parts  of  the  State  where 
apples  are  grown.  The  Division  has  been  carrying  on  spraying  in- 
vestigations in  cooperation  with  growers  in  an  effort  to  determine 
the  best  method  of  control  for  this  disease.  Results  thus  far  indi- 
cate the  best  success  from  treatment  with  sulphur-  or  sulphide- 
containing  sprays  in  the  spring  and  early  summer. 

TOMATO    DISEASES. 

The  investigation  of  tomato  diseases  has  received  considerable 
attention  ever  since  the  beginning  of  the  southern  California  work. 
One  of  the  most  important  branches  of  tomato  growing  in  that  sec- 
tion has  come  to  be  the  crop  which  is  matured  late  in  the  fall  for 
eastern  shipment.  This  enterprise  has  proven  extremely  successful, 
except  for  one  drawback.  This  is  the  prevalence  of  the  common 
potato-blight  fungus  (Phytophthora  infestans) ,  attacking  the  tomato 
vines  in  seasons  when  rain  occurs  early  in  the  fall.  During  the  fall 
of  1907  the  whole  acreage  of  tomatoes  was  completely  ruined  in  this 
manner  before  active  shipments  had  begun,  making  the  crop  a  total 
loss.  Demonstrations  by  the  Laboratory  at  that  time,  however,  showed 
the  possibility  of  entirely  controlling  this  disease  by  means  of  spray- 
ing the  vines  with  Bordeaux  mixture  following  the  rain.  Prepara- 
tions were  made  by  this  Division  and  by  the  growers  to  carry  out 
such  spraying  on  a  large  scale  during  the  season  of  1908,  should 
weather  conditions  make  it  necessary.  The  season  was  not  such,  how- 
ever, as  to  favor  the  extensive  development  of  the  blight,  so  that 
extensive  spraying  was  not  required.  Such  spraying,  however,  like 
all  other  work  of  the  same  sort,  is  of  the  nature  of  insurance  and 
should  be  prepared  for  each  year,  whether  conditions  make  it  neces- 
sary or  not. 

The  method  of  procedure  in  regard  to  the  spraying  operation 
itself  is  a  very  simple  one,  consisting  in  spraying  the  vines  thoroughly 
with  Bordeaux  mixture,  made  by  mixing  together  blue  stone  (copper 
sulphate)  and  lime  water,  using  5  pounds  of  the  former  and  5 
pounds  of  unslaked  lime  to  50  gallons  of  water.  The  blue  stone  is 
dissolved  and  the  lime  slaked  in  separate  portions  of  water,  and  the 
two  then  diluted  and  mixed  together,  running  them  through  a  strainer. 
The  chief  problem  involved  is  much  the  same  as  that  with  the  celery 
disease;  namely,  that  of  getting  a  large  acreage  properly  sprayed  at 
the  proper  time.     It  is  to  this  phase  of  the  matter  in  each  instance 


Bulletin  203.  REPORT  OP  PLANT  PATHOLOGIST.  45 

that  this  Division  is  paying  particular  attention,  working  through 
the  cooperative  associations  into  which  the  growers  of  these  crops 
are  united. 

Considerable  work  of  an  experimental  nature  has  been  carried 
on  at  the  Whittier  Laboratory  on  the  subject  of  the  prevention  of 
damping  off  of  tomato  plants  in  the  seed  bed  by  chemical  soil  treat- 
ment. This  trouble  causes  severe  loss  almost  every  season,  both  in 
tomato  and  other  plants.  Our  results  thus  far  have  not  been  espe- 
cially promising.  The  experiments  have  been  mainly  in  the  treat- 
ment of  soil  with  dilute  solution  of  formaldehyde  and  sulphuric  acid. 

The  best  results  in  growing  plants  have  been  obtained  by  careful 
attention  to  proper  watering  and  soil  preparation,  obtaining  as  thrifty 
and  vigorous  a  growth  as  possible  without  oversaturation  of  the  soil 
with  water. 

TECHNICAL   INVESTIGATIONS   IN  PLANT   PATHOLOGY. 

In  addition  to  these  more  practical  lines  of  work  having  immediate 
field  application,  the  very  favorable  resources  of  the  Whittier  Labora- 
tory are  also  being  made  use  of  for  various  lines  of  technical  re- 
search in  connection  with  the  work  of  this  Division.  Opportunities 
are  offered  for  the  work  of  graduate  students  at  the  Laboratory  in 
special  investigations.  Work  of  this  nature  which  has  been  going 
on  includes  an  investigation  of  various  species  of  Fusarium,  sup- 
posed to  be  the  cause  of  diseases  of  various  plants;  also  the  study  of 
several  of  the  so-called  physiological  plant  diseases,  based  particularly 
on  the  "Curly  Top"  of  the  sugar-beet  and  the  aster  "Yellows." 

WOEK   IN   ENTOMOLOGY   AT    THE    SOUTHERN   CALIFORNIA 
LABORATORY. 

The  work  and  usefulness  of  the  Whittier  Laboratory  has  been 
greatly  broadened  during  the  past  year  by  the  commencement  of 
investigations  in  entomology  by  Professor  Quayle.  The  problems  of 
insect  control  in  Southern  California  have  received  an  unusual  amount 
of  attention  from  a  purely  economic  standpoint,  but  until  recently 
there  has  been  very  little  careful  investigation  made  concerning  de- 
structive insects  of  this  portion  of  the  State  from  a  biological  stand- 
point. Among  the  important  problems  in  entomology  those  concern- 
ing citrus  insects  are  much  the  most  prominent,  particularly  in  the 
case  of  certain  scale  insects.  Mr.  Quayle  has  therefore  devoted  his 
principal  attention  to  the  commencement  of  a  thorough  study  of  the 
biology  of  the  most  important  insect  enemies  of  citrus  trees.  Chief 
among  these  are  the  four  scale  insects  which  are  most  prominent,  the 


46  UNIVERSITY  OF  CALIFORNIA EXPERIMENT  STATION. 

so-called  black,  purple,  red,  yellow,  and  soft  brown  scales  (Saissetia 
oleae  Bern.,  Lepidosaphes  beckii  Newm.,  Chrysomphalus  aurantii 
Mask.,  Chrysomphalus  aurantii  var.  citrinus  Coq.,  and  Coccus  hes- 
peridum  Linn.) 

Each  of  these  species  has  received  careful  study  in  the  field,  lab- 
oratory and  insectary  to  determine  exactly  its  life  habits  and  the 
whole  course  of  its  development.  Other  citrus  insects  which  are  also 
receiving  attention  are  the  mealy  bug  (Pseudococcus  citri  Risso.) 
and  the  cottony  cushion  scale  (Icerya  purchasi  Mask).  It  is  our  in- 
tention to  continue  and  extend  these  studies  in  the  future  and  also 
to  build  up  collections  of  southern  California  insects,  and  in  other 
ways  to  make  the  Whittier  Laboratory  a  center  of  entomological  re- 
search in  southern  California. 

CITRUS    CULTURE    AND    DISEASES. 

One  of  the  most  important  undertakings  of  this  Division  is  the 
study  of  citrus  culture,  this  work  being  prominent  both  at  the  Whit- 
tier Laboratory  and  at  the  Riverside  Station.  The  whole  subject  of 
citrus  culture  demands  more  and  more  attention  from  scientific  in- 
vestigation as  the  industry  grows  older,  and  the  station  founded  at 
Riverside  especially  to  meet  this  demand  has  possibilities  of  a  most 
useful  development,  while  at  the  same  time  its  responsibilities  to  the 
industry  are  great. 

The  commencement  of  this  citrus  work  under  the  direction  of  the 
Division  of  Plant  Pathology  should  by  no  means  be  looked  upon  as 
an  indication  of  a  narrow  scope  or  limited  field  in  the  future  of  the 
work,  or  that  it  is  expected  that  its  many  phases  will  be  covered  in 
a  superficial  manner  by  work  from  a  single  standpoint.  It  is  rather 
the  intention  to  make  these  Stations  centers  of  research  on  problems 
relating  to  citrus  culture,  developing  facilities  and  special  depart- 
ments as  rapidly  and  efficiently  as  possible. 

Disease  Investigations. — The  study  of  diseases  or  failures  of  citrus 
trees  in  California  is  a  most  complicated  problem.  This  is  due  to 
the  fact  that  the  chief  troubles  are  not  of  parasitic  origin,  but  are 
due  to  abnormal  physiological  conditions  brought  about  by  the  arti- 
ficial environment  under  which  the  trees  are  grown.  The  exact 
nature  of  these  troubles  is  in  most  cases  extremely  difficult  of  deter- 
mination, while  a  demonstration  of  a  remedy  or  corrective  for  the 
same  is  even  more  difficult.  The  case  is  very  different  from  those 
where  fungus  or  similar  diseases  occur.  In  fact,  it  is  not  entirely 
a  question  of  health  and  disease  with  the  citrus  crop,  but  rather  one 
of  commercial  perfection  and  its  opposite;  in  other  words,  the  per- 


Bulletin  203.  REPORT  OF  PLANT  PATHOLOGIST.  47 

fection  of  desirable  commercial  qualities  is  by  no  means  the  same 
as  natural  development  or  natural  health.  The  fact  is  that  the  work 
of  the  plant  pathologist  in  California  with  citrus  fruits  is  not  lim- 
ited to  the  studjr  of  actual  disease  and  the  means  of  avoiding  it.  He 
is  rather  called  upon  to  advance  commercial  perfection  and  learn  how 
to  overcome  conditions  which  are  undesirable  from  this  standpoint, 
whether  they  be  ones  of  actual  disease  or  not.  For  this  reason  it  is 
natural  that  problems  of  soil  fertilization  and  other  cultural  consid- 
erations should  be  closely  associated  with  the  work  of  the  pathologist, 
since  they  cannot  be  sharply  segregated. 

A  thorough  study  of  what  may  be  called  the  actual  diseases  of 
citrus  trees  in  this  State  is  being  carried  on  in  Southern  California, 
both  in  the  field  and  laboratory.  As  a  result  of  this  work  thus  far 
it  may  be  said  in  general  in  regard  to  citrus  diseases  that  almost 
nothing  has  been  found  which  may  be  ascribed  to  the  effects  of  any 
parasite.  If  we  except  decay  of  the  fruit  and  a  very  few  minor  cases, 
the  above  statement  may  be  made  an  absolute  one.  It  is  a  fact  beyond 
question  that  the  most  serious  troubles  with  citrus  trees  in  California 
are  the  effects  of  unfavorable  natural  conditions  and  not  those 
of  fungi,  bacteria  or  other  parasites.  Some  of  these  effects  are  at 
present  most  obscure,  and  difficult  or  impossible  to  account  for  in 
any  satisfactory  manner.  Yet  the  study  of  the  various  diseases  and 
of  the  nature  of  the  tree  itself  has  been  sufficient  to  show  that  the 
above  statement  is  true. 

The  citrus  disease  investigation  is  being  conducted  in  the  field 
by  various  members  of  the  staff,  while  a  large  amount  of  more  tech- 
nical work  is  being  done  at  the  Whittier  Laboratory  in  the  prepara- 
tion and  microscopic  study  of  affected  tissues. 

The  particular  diseases  or  troubles  under  consideration  at  present 
may  be  named  as  follows:  Gum  disease  of  the  lemon,  scaly  bark  of 
the  orange,  Florida  die-back  (Exanthema)  of  the  orange,  puffing, 
splitting,  brown  spot  and  staining  of  the  orange,  and  pitting  of  the 
lemon.  These  are  all  serious  troubles  affecting  very  materially  the 
production  of  groves  and  the  financial  returns  from  the  fruit.  The 
results  of  investigations  on  the  first  three  subjects  mentioned  have  been 
reported  in  Bulletin  200,  "Gum  Disease  of  the  Citrus  Trees  in  Cali- 
fornia." In  this  work  the  nature  of  these  diseases  was  quite  fully 
established  and  practical  means  of  control  demonstrated. 

The  so-called  "brown  spot"  of  the  orange  is  a  subject  which  re- 
ceived considerable  attention  during  the  past  year.  This  is  a  pecul- 
iarly obscure  problem,  and  no  positive  results  have  been  obtained  as 
to  the  nature  of  the  trouble  or  methods  for  its  control.     The  disease 


48 


UNIVERSITY  OF  CALIFORNIA — EXPERIMENT  STATION. 


Fig.  21. — Orange  scaly  bark. 


Bulletin  203.  REPORT  OF  PLANT  PATHOLOGIST.  49 

shows  itself  in  the  form  of  dark-brown  sunken  spots  of  considerable 
size  on  the  surface  of  the  orange.  These  spots  are  not  visible  while 
the  fruit  is  on  the  tree  or  when  freshly  picked,  but  develop  within 
two  or  three  weeks  after  picking,  thus  appearing  mostly  after  the 
fruit  has  reached  the  eastern  markets.  The  spot  affects  the  most 
fancy,  smoothest  fruit  worst  and  occurs  abundantly  only  in  certain 
sections.  We  feel  safe  in  saying  that  it  is  not  caused  by  any  insect, 
fungus,  bacterium  or  other  living  parasite  and  is  not  the  effect  of 
fumigation,  spraying,  ordinary  frost  or  any  such  thing.  The  spot 
itself  is  simply  a  portion  of  the  rind  which  weakens  prematurely  and 
becomes  dead,  dry  and  dark  colored.  Some  influence  must  act  upon 
the  fruit  at  some  time  previous  to  the  beginning  of  the  picking  season 
which  causes  the  rind  to  be  injured  or  weakened  in  these  spots.  It 
seems  most  likely  that  this  influence  is  connected  with  some  climatic 
condition  peculiar  to  the  region  in  which  the  trouble  occurs.  A  large 
amount  of  negative  information  was  obtained  during  the  past  season 
which  is  not  without  value  in  simplifying  and  more  clearly  defining 
the  problem.  The  work  will  be  renewed  next  season  in  a  further 
effort  to  discover  the  real  nature  of  this  spotting. 

In  addition  to  these  more  specific  diseases,  investigation  is  needed 
in  many  cases  of  failures  or  troubles  with  trees  which  are  occurring 
abundantly.  This  work  commonly  involves  soil  studies  and  chemical 
investigations  of  various  sorts,  and  herein  is  illustrated  the  close  cor- 
relation of  such  investigations  with  plant  pathology  proper  in  citrus 
work. 

Soil  and  Fertilizer  Work. — The  work  on  citrus  culture  in  gen- 
eral which  has  thus  far  received  the  most  attention  is  that  relating 
to  the  fertilization  of  the  soil.  This  is  one  of  the  most  important  and 
at  the  same  time  most  complicated  problems  which  face  the  California 
citrus  grower.  The  attention  of  the  Experiment  Station  for  many 
years  has  been  directed  to  a  considerable  extent  in  this  direction, 
yet  as  the  industry  advances  the  demand  for  information  becomes 
more  and  more  specific,  and  the  problems  more  and  more  obscure. 
If  the  general  vigor  and  growth  of  the  trees  were  the  only  question 
involved,  or  even  their  quantitative  product,  present  knowledge  would 
be  fairly  sufficient.  With  the  problem  complicated  by  the  relation 
of  fertilization  to  certain  definite  qualities  of  the  fruit,  desirable  and 
undesirable,  likewise  questions  affecting  the  physical  quality  of  the 
soil  and  its  treatment,  the  mere  matter  of  fertility  becomes  almost 
of  secondary  importance.  A  large  amount  of  investigation  of  the 
matter  from  many  different  standpoints  will  be  needed  to  make  the 
Citrus  Experiment  Station  a  practical  success,  measured  by  the  de- 


50  UNIVERSITY  OF  CALIFORNIA — EXPERIMENT  STATION. 

mands  awaiting  it.  As  a  fundamental  basis  of  the  work  upon  fer- 
tilization, it  has  seemed  desirable  to  determine  more  definitely  than 
is  now  known  the  specific  effects  of  the  various  fertilizing  elements 
upon  citrus  fruit.  For  this  purpose  a  ten-acre  planting  of  young 
trees  has  been  started,  as  described  in  Circular  35,  made  up  of 
twenty  small  plots,  upon  which  the  application  of  the  various  single 
elements  and  combinations  has  been  begun.  This  should  show  more 
definitely  than  is  known  at  present  the  results  of  such  applications. 
Similar  experiments  have  also  been  begun  to  a  limited  extent  upon 
trees  of  mature  size  in  an  orchard  adjoining  the  Station  grounds, 
which  has  been  leased  for  this  purpose. 

Other  fertilizer  experiments  have  also  been  begun  for  the  pur- 
pose of  testing  the  effects  of  certain  materials  and  also  in  regard  to 
different  amounts  of  complete  fertilizer  as  affecting  the  comparative 
amount  of  the  fruit.  A  series  of  cooperative  fertilizer  experiments, 
which  was  begun  by  the  Experiment  Station  several  years  ago  under 
the  direction  of  Professor  Stubenrauch  and  carried  on  by  Mr.  J. 
W.  Mills,  has  been  continued  by  the  Citrus  Station.  In  the  majority 
of  cases,  however,  these  experiments  were  not  continued  long  enough 
by  the  various  growers  in  whose  groves  they  were  being  carried  on 
to  give  any  definite  results.  Only  a  very  few  are  being  kept  up  at 
present,  and  the  uncertain  nature  of  the  results  even  in  these  is  suf- 
ficient to  show  the  extreme  difficulty  of  conducting  satisfactory  fer- 
tilizer demonstrations  in  the  ordinary  grove,  although  cooperative 
experiments  of  a  simple  nature  adapted  to  commercial  practice  can 
be  arranged  with  growers  in  various  sections.  This  has  been  done 
already  to  some  extent  by  the  Citrus  Station  since  its  establishment, 
carrying  out  demonstrations  on  the  improvement  of  unfertilized 
groves  by  the  use  of  complete  fertilizers  in  different  amounts,  the 
application  of  specific  elements  in  certain  cases  and  other  similar  un- 
dertakings. 

The  work  of  the  Station  concerning  soil  nature  and  treatment  has 
been  greatly  broadened  during  the  past  year  by  the  appointment  of 
Professor  Norton  to  our  staff.  His  work  has  been  commenced  along 
the  line  of  seeking  more  accurate  information  and  data  in  connection 
with  soil  treatment  than  is  now  available.  The  principal  problem 
upon  which  his  investigations  have  been  begun  is  that  connected  with 
the  addition  of  humus  to  the  soil.  Careful  studies  have  been  started 
concerning  the  various  cover  crops  on  the  basis  of  measurement 
of  tonnage  produced,  chemical  analysis  and  the  question  of  nitrogen 
fixation,  the  latter  in  connection  with  pot  experiments.  Other  im- 
portant problems  relating  to  soil  improvement,  fertilizer,  etc.,  will  be 


Bulletin  203.  report  of  plant  pathologist.  51 

taken  up  and  this  work  laid  out  on  a  permanent  and  thorough  basis. 
Professor  Norton  will  also  be  able  to  devote  some  attention  to  crops 
other  than  citrus  in  connection  with  his  soil  studies  and  chemical 
work. 

Pomological  Work. — A  beginning  has  been  made  at  the  Riverside 
Station  of  considerable  work  of  a  pomological  nature  in  relation  to 
citrus  fruit.  This  includes  particularly  the  improvement  of  vari- 
eties by  bud  selection  and  the  testing  of  various  citrus  species  for 
root  stocks.  A  considerable  nursery  has  been  started  in  which  are 
growing  orange  and  lemon  trees  which  have  been  selected  from  trees 
showing  various  peculiar  characteristics  of  a  desirable  kind,  and  also 
a  large  amount  of  root  stock  of  various  species. 

The  addition  of  Professor  Coit  to  our  -staff  will  give  greater 
breadth  and  strength  to  work  along  pomological  lines. 


VARIETY  INTRODUCTION  AND  TESTING  OF  PECANS, 
PEACHES  AND  TOMATOES. 

The  facilities  available  at  Whittier  and  Riverside  for  growing 
trees  and  plants  has  made  possible  a  beginning  of  the  introduction 
and  testing  of  various  cultures  of  certain  sorts. 

Pecans. — The  growing  importance  of  pecan  culture  in  the  southern 
states  has  awakened  considerable  interest  in  the  possibility  of  the 
production  of  these  nuts  in  California.  The  subject  was  brought  to 
the  attention  of  this  Station  through  its  work  with  walnuts,  and, 
being  of  a  similar  nature,  has  been  given  some  attention.  Pecan  trees 
are  growing  in  various  parts  of  California  and  thrive  well.  Their 
production  is  a  matter  of  much  variation  in  different  sections  and 
with  different  trees.  In  general,  however,  the  interior  valleys  of  the 
State  where  the  summers  are  hot  and  the  winters  fairly  cold  seem 
better  adapted  to  pecan  culture  than  the  coast  regions.  Many  trees 
in  the  State  fail  to  produce,  or  ripen  their  nuts  very  irregularly,  on 
account  of  the  mild  climate  and  lack  of  definition  of  the  seasons. 

Of  the  many  improved  varieties  of  pecans  which  are  now  being 
grown  in  Texas,  Florida,  Georgia,  Louisiana,  Mississippi,  etc.,  very 
few  have  been  tested  in  California,  and  none  for  a  long  enough  time 
or  generally  enough  to  demonstrate  their  adaptability  to  this  State. 
During  the  winter  of  1908  trees  were  obtained  by  this  Division  of  about 
thirty  of  the  leading  varieties  from  various  nurseries  in  the  southern 
states.  These  were  planted  on  the  grounds  of  the  Whittier  Labora- 
tory and  are  all  growing  well  at  present.     A  large  number  of  pecan 


52 


UNIVERSITY  OF  CALIFORNIA EXPERIMENT  STATION. 


nuts  were  also  planted  in  the  nursery,  and  upon  these  seedlings  the 
various  varieties  will  be  propagated  and  the  trees  thus  obtained  dis- 
tributed for  trial  in  different  parts  of  the  State.  In  the  spring  of 
1908  trees  of  a  few  varieties  obtained  from  nurseries  were  also 
planted  at  a  few  different  points  in  the  State  for  the  same  purpose 
of  demonstration. 


Fig.  22. — Pecans:    Large  variety  is  Frotscher,  the  others 
seedlings,  showing  variation  in  size  and  shape. 


Peaches. — Another  somewhat  similar  project  has  been  begun  with 
peaches  adapted  to  growth  in  southern  California.  In  this  section 
of  the  State  the  production  of  the  usual  commercial  varieties  has 
been  quite  uncertain,  owing  to  the  mildness  of  the  winter  climate. 
The  success  in  Florida  and  other  southern  regions  of  many  varieties 
of  the  Honey  and  other  Chinese  peaches  has  suggested  the  possibility 
of  developing  varieties  from  such  a  source  of  value  in  southern  Cali- 
fornia. For  this  purpose  buds  of  a  large  number  of  varieties  were 
obtained  from  Florida  in  1906  and  trees  from  these  are  now  being 
grown  for  testing  and  distribution. 

Tomatoes. — In  certain  sections  of  southern  California  a  valuable 
industry  exists  in   growing  tomatoes   for  shipment  during  the  late 


Bulletin  203.  report  of  plant  pathologist.  53 

fall  and  early  winter.  These  are  planted  in  the  field  in  July  and 
set  a  large  amount  of  fruit  during  the  latter  part  of  the  summer, 
which  matures  at  a  time  when  eastern  tomatoes  have  been  killed  by 
frost.  For  this  purpose  varieties  are  desirable  of  good  appearance 
and  shipping  quality,  and  also  such  as  will  continue  to  set  fruit  well 
into  the  winter.  The  variety  most  commonly  planted  at  present,  the 
Stone,  is  quite  satisfactory  for  this  purpose,  but  a  number  of  other 
kinds  are  being  tested  at  Whittier  with  the  idea  of  obtaining  the 
best  variety  for  the  exacting  requirements  of  this  shipping  crop. 
Most  of  this  work  has  been  done  with  the  assistance  of  Mr.  R.  E. 
Mansell,  of  the  Experiment  Station  at  Berkeley. 

EUCALYPTUS    INVESTIGATIONS. 

A  very  careful  study  has  been  made  under  the  direction  of  this 
Division  by  Mr.  Ingham,  of  the  Forestry  Station,  of  the  present  con- 
dition, prospects  and  methods  of  Eucalyptus  culture  in  California. 
The  growth  of  these  trees  of  many  different  species  has  been  studied 
all  over  the  State  and  their  adaptation  determined  in  the  various 
sections.  As  a  result  of  this  study  a  bulletin  has  been  prepared, 
entitled  "Eucalyptus  in  California."  This  includes  a  discussion  of 
the  growing  of  Eucalyptus  as  a  crop,  the  methods  of  the  same,  the 
utilization  of  the  wood  and  descriptions  of  the  important  species. 
Following  the  preparation  of  this  bulletin  other  work  has  been  taken 
up  upon  the  commercial  utilization  of  Eucalyptus  wood  for  lumber, 
its  qualities,  uses,  methods  of  handling,  etc.  This  has  been  taken 
up  in  a  practical  way  by  fitting  up  a  small  woodworking  shop  at 
the  Santa  Monica  Station,  where  a  great  variety  of  samples  is  being 
prepared  under  Mr.  Ingham's  direction,  showing  the  wood  of  the 
various  species.  These  collections  have  been  placed  on  exhibition 
and  the  work  is  being  followed  by  further  investigations  along  the 
same  line. 

Some  work  has  also  been  done  in  the  study  of  the  extraction  of 
oil  from  the  foliage  of  various  kinds  of  Eucalyptus.  The  oils  ob- 
tained from  the  different  species  vary  quite  widely  in  their  character. 

WOKK  IN  IMPEEIAL  VALLEY. 

The  great  Imperial  Valley  region  in  the  extreme  southeastern 
part  of  California  presents  many  serious  problems  in  plant  pathol- 
ogy as  well  as  other  lines  of  agricultural  investigation.  The  rapid 
development  of  agriculture  under  the  extremely  unusual  natural  con- 
ditions of  that  region  has  been  accompanied  with  many  grave  prob- 
lems affecting  the  prosperity  of  the  industry.     As  a  result  of  this, 


54  UNIVERSITY  OF  CALIFORNIA — EXPERIMENT  STATION. 

there  has  been  a  strong  demand  for  a  sub-station  or  some  sort  of 
local  irfstitution  for  agricultural  investigation  in  that  part  of  the 
State.  In  response  to  this  demand  the  following  Act  was  passed  by 
the  last  legislature: 

' '  An  Act  Making  an  Appropriation  for  the  Investigation  of  Agricultural  and 
Horticultural  Problems  and  Conditions  in  Imperial  County,  and  Providing  for 
the  Establishment  in  Said  County  of  a  Branch  Agricultural  Experiment  Station 
for  the  Purpose  of  Prosecuting  said  work. 

' '  The  people  of  the  State  of  California,  represented  in  senate  and  assembly, 
do  enact  as  follows: 

11  Section  1.  The  regents  of  the  University  of  California  are  hereby  directed 
to  cause  to  be  prosecuted,  through  the  Southern  California  Pathological  Labora- 
tory and  branch  experiment  station,  investigations  on  the  conditions  and  prob- 
lems attending  the  culture  of  crops  in  the  region  known  as  the  Imperial  county 
and  similar  adjacent  sections. 

"Sec.  2.  Such  investigations  shall  be  particularly  directed  toward  the  solu- 
tion of  various  difficulties  and  problems  affecting  the  growing  of  crops,  which 
have  arisen  in  said  region  on  account  of  the  unique  natural  conditions  obtaining 
in  that  portion  of  the  state. 

"Sec.  3.  The  regents  of  the  University  of  California  are  hereby  authorized 
to  establish  at  some  suitable  point  in  Imperial  county  a  branch  agricultural 
experiment  station  for  the  purpose  of  carrying  on  the  work  herein  provided  for; 
provided  the  necessary  land  therefor  is  obtained  without  cost  to  the  state. 

"Sec.  4.  The  sum  of  six  thousand  dollars  ($6,000)  is  hereby  appropriated 
out  "of  any  money  in  the  state  treasury  not  otherwise  appropriated  to  be  ex- 
pended by  the  regents  of  the  University  of  California  in  carrying  out  the  pur- 
poses of  this  act,  and  the  state  controller  is  hereby  authorized  and  directed  to 
draw  his  warrant  for  the  same  payable  to  the  regents  of  the  University  of  Cali- 
fornia, and  the  treasurer  of  the  state  is  hereby  directed  to  pay  such  warrant." 

Section  3,  concerning  the  establishment  of  a  station,  constitutes 
a  subsequent  addition  to  the  original  bill  and  can  hardly  be  com- 
plied with  on  the  basis  of  the  appropriation  granted  for  this  purpose. 
The  original  idea  was  that  of  conducting  preliminary  investigations 
and  observations  with  these  problems  rather  than  establishing  a  per- 
manent station  at  once.  The  work  had  not  yet  been  organized  at 
the  close  of  the  period  covered  by  this  report,  but  will  be  undertaken 
along  whatever  lines  seem  most  suitable. 

PASADENA  CITY   FARM. 

An  informal  cooperative  arrangement  has  been  made  by  this  Divi- 
sion during  the  past  year  with  the  city  of  Pasadena  in  regard  to 
the  development  of  a  large  tract  of  land  owned  by  the  city  and  used 
as  a  sewer  farm.  This  land  comprises  over  five  hundred  acres  of 
varied  and  mostly  excellent  quality,  and  supports  at  present  about 
one  hundred  acres  of  English  walnuts  and  large  crops  of  hay,  grain, 


Bulletin  203.  REPORT  OF  PLANT  PATHOLOGIST.  55 

corn  and  alfalfa.  One  of  the  greatest  handicaps  of  this  Division 
in  southern  California  has  been  the  lack  of  sufficient  land  for  making 
plantings  on  a  commercial  scale  of  walnuts,  citrus  fruits,  and  vari- 
ous other  crops  in  connection  with  which  work  is  being  done.  The 
arrangement  proposed  by  the  city  of  Pasadena  seems  to  fill  this  want 
in  an  almost  ideal  manner.  The  work  can  be  done  at  practically  no 
extra  cost  to  the  Experiment  Station  and  can  be  made  of  value  to 
Pasadena  and  other  cities  having  sewage  problems,  in  addition  to 
the  results  that  may  be  obtained  from  the  regular  lines  of  agricul- 
tural experimentation.  Active  work  has  already  been  begun  on  this 
project  by  planting  a  number  of  varieties  of  our  walnuts  for  trial 
and  grafting  over  of  old  trees.  A  citrus  nursery  has  also  been  started 
and  during  the  coming  year  a  large  amount  of  other  nursery  material 
will  be  planted  on  the  farm. 


56  UNIVERSITY  OF  CALIFORNIA EXPERIMENT  STATION. 


PLANT  DISEASES  OF  CALIFORNIA. 

The  following  list  contains  a  number  of  additional  diseases  to 
those  given  in  our  last  report,  as  well  as  notes  on  the  occurrence  of 
the  more  serious  troubles  during  the  period  covered.  In  general, 
the  prevalence  of  plant  diseases  during  the  year  1907  was  of  about  an 
average  extent.  The  more  common  troubles  occurred  as  extensively 
as  usual,  or  on  the  whole  rather  more  so.  The  year  1908  was  marked 
by  a  very  noteworthy  freedom  from  fungous  and  bacterial  plant  dis- 
eases of  all  sorts.  This  evidently  resulted  from  the  dry  winter  of 
1907-8  and  the  prevalence  of  dry,  windy  weather  during  much  of 
the  season  all  over  the  State.  Thus  the  relation  of  climate  to  the 
occurrence  of  parasitic  diseases  was  a  most  notable  feature  of  the 
fruit  season  of  1908  in  California.  No  general  rule  prevailed  in  1909, 
some  diseases  being  more  abundant  than  usual  and  others  noticeably 
absent. 

POME   FEUITS. 
Apple. 

Powdery  Mildew. — This  disease  has  proven  an  exception  to  the 
condition  above  stated,  being  more  prevalent  than  usual  during  1908. 
It  is  one  of  the  serious  troubles  of  the  apple  orchard  in  this  State. 
Investigations  on  the  control  of  the  disease  have  been  carried  on  to 
some  extent  by  this  Division,  as  reported  elsewhere.  Very  prevalent 
in  1909. 

Blight. — Attacks  of  the  pear  blight  bacillus  upon  the  apple  occur 
to  a  limited  extent,  although  no  very  serious  results  have  occurred. 
The  disease  was  prevalent  to  some  extent  on  apples  in  1908,  although 
less  in  general  than  in  previous  years.    Not  commonly  serious  in  1909. 

Canker  (Nectria  ditissima). — This  fungous  disease  has  been  found 
in  the  State,  but  is  not  a  serious  trouble  in  commercial  orchards. 

"Baldwin  Spot." — Troubles  of  this  nature  are  becoming  serious 
in  California.  In  some  sections  the  crop  has  been  badly  aifected  by 
the  development  of  discolored  spots  or  streaks  in  the  interior  of  the 
apple  from  an  unknown  cause.  No  evidence  is  present  of  any  para- 
sitic attack. 

Pear. 

Scab. — Pear  scab  was  extremely  prevalent  in  1907  and  injured  the 
quality  of  the  crop  greatly.     Thorough  spraying  with  Bordeaux  mix- 


Bulletin  203.  report  of  PLANT  PATHOLOGIST.  57 

ture,  beginning  when  the  buds  first  unfold  and  repeated  later  at  in- 
tervals, showed  excellent  results  as  usual  in  controlling  the  disease. 
In  1908  and  1909  pear  scab  was  almost  entirely  absent  from  the  State. 

Blight. — Pear  blight  prevailed  to  a  considerable  extent  in  1907 
and  continued  the  destruction  of  many  trees  which  began  with  the 
epidemic  of  1904.  In  1908  and  1909  the  occurrence  of  the  disease 
was  very  much  reduced,  and  in  many  sections  it  disappeared  almost 
entirely.  This  was  due  to  climatic  causes  and  does  not  indicate  a 
permanent  subsidence  of  the  disease. 

Curly  Bark. — A  very  common  but  not  serious  condition  of  pear 
trees  may  be  called  by  this  name.  It  is  shown  by  areas  of  bark  which 
are  cracked  in  a  peculiar  concentric  manner,  as  the  name  indicates. 
Its  occurrence  is  a  matter  of  very  little  concern. 

LOQUAT. 

Scab. — The  leaves  and  fruit  are  affected  to  considerable  extent  in 
the  San  Francisco  Bay  region  by  the  fungus  Fusicladium  eriobotryae. 
Also  found  at  Santa  Barbara  and  Whittier  in  1909. 

STONE    FETJITS. 
Apricot. 

Dead  Flower  Buds. — A  large  acreage  was  badly  affected  in  1907 
by  a  killing  of  the  flower  buds  before  opening,  apparently  by  the 
peach  blight  fungus,  Coryneum.  Much  less  prevalent  in  the  spring 
of  1908;  more  abundant  in  1909. 

Fruit  Scab  (Cladosporium  carpophilum) . — So  far  as  known,  this 
is  the  first  record  of  Cladosporium  spot  on  apricots.  It  is  rather 
troublesome  in  some  districts. 

Fruit  spot  and  shot-hole  of  leaf  (Coryneum). — Quite  serious  on 
unsprayed  trees. 

Almond. 

Shot-hole  Fungus  (Cercospora  circumscissa) . — This  is  of  rather 
frequent  occurrence,  causing  spotting  of  the  leaves  and  twigs. 

Cherry. 

Brown  Rot  (Sclerotinia) . — Fruit  and  twigs  of  the  cherry  affected 
with  the  brown  rot  fungus  were  seen  in  the  spring  of  1908. 
Gummosis. — Quite  abundant  in  wet  winters. 

Peach. 

Leaf  Curl  and  California  Blight. — Were  decidedly  scarce  in  1908. 
Both  occurred  to  greater  extent  in  the  previous  year.  Leaf  curl  was 
very  abundant  in  1909;  blight  not  very  abundant. 


58  UNIVERSITY  OF  CALIFORNIA EXPERIMENT  STATION. 

Crown  Gall. — Our  most  prevalent  disease  of  stone  fruit  trees. 
Root  Rot  {Toadstool  or  Oak  Fungus). — Causing  extensive  losses 
in  deciduous  fruit  orchards  located  on  cleared  oak  land. 

SMALL  FRUITS. 
Loganberry. 

Rust   (Puccinia  peckiana). — Common. 
Leaf  Spot   (Septoria  rubi). — Common. 
Root  Knot. — Not  uncommon. 

SUBTROPICAL    FRUITS. 
Orange. 

Scaly  Bark. — This  trouble  consists  in  a  rough  breaking  out  of  the 
bark  on  the  trunk  and  branches  of  oranges,  starting  in  a  small  area 
and  greatly  enlarging.  It  is  a  form  of  gum  disease  and  cannot  be 
connected  with  any  parasite.  The  trouble  is  an  old  one  in  the  State 
and  is  quite  like  that  described  in  the  Annual  Report  of  the  Florida 
Experiment  Station  for  1907. 

Mai  di  gomma. — The  typical  form  of  this  disease,  as  described 
from  Florida  and  elsewhere  as  a  rotting  of  the  roots,  is  not  of  com- 
mon occurrence  in  California,  although  a  few  bad  cases  have  been 
seen. 

Exanthema. — The  disease  described  in  Florida  under  this  name 
occurs  in  southern  California  to  a  limited  extent  and  almost  entirely 
on  one  type  of  soil.  This  is  the  coarse,  gravelly,  very  porous  material, 
occurring  close  to  the  mountains  in  some  sections.  The  trouble  ap- 
pears to  be  due  to  irregular  nutrition,  owing  to  the  very  loose  nature 
of  the  soil.  A  few  cases  have  been  seen  on  heavier  soils  where  ex- 
cessive amounts  of  organic  nitrogen  have  been  applied.  Experience 
appears  to  have  demonstrated  some  benefit  in  this  disease  by  spray- 
ing the  trees  with  Bordeaux  mixture.  How  this  comes  about  is  diffi- 
cult to  explain,  except  on  the  basis  of  an  increased  assimilation  as 
an  effect  of  the  presence  of  the  spray  upon  the  leaves. 

Splitting. — Considerable  losses  are  experienced  some  years  by  a 
splitting  of  oranges  before  maturity.  This  affects  particularly  the 
Navels.  It  is  evidently  influenced  by  climatic  conditions  and  is  not 
the  effect  of  a  parasite.  The  trouble  was  very  prevalent  in  the  crop 
of  1907-08 ;  much  less  abundant  in  1908-09. 

Brown  Spot  and  Staining. — These  troubles  occurred  to  a  serious 
extent  during  the  winter  of  1908.     They  are  characterized  by  the 


Bulletin  203.  REPORT  OF  PLANT  PATHOLOGIST.  59 

dying  and  discoloration  of  the  surface  of  the  rind  in  certain  spots 
or  areas,  causing  the  disfiguration  of  the  fruit.  They  were  less  abun- 
dant in  1909,  except  in  certain  sections. 

Navel  Rot  (Altemaria  citri). — This  fungus  causes  considerable 
loss  each  year  in  Navel  oranges  by  infection  at  the  navel  opening 
and  the  production  of  a  black,  dry  rot.  The  fungus  is  not  very  active 
in  its  development,  but  spoils  much  fruit  in  wet  winters.  Affected 
fruit  becomes  prematurely  ripe  before  the  decay  is  visible  externally. 

Damping  Off. — Much  loss  is  caused  in  citrus  seed  beds  by  the 
killing  of  young  plants  by  ''damping  off"  fungi.  This  is  caused 
most  commonly  by  two  parasites,  one  a  species  of  Fusarium  and  the 
other  Rhizoctonia.  The  development  of  these  fungi  is  particularly 
favored  by  moisture  and  the}'  can  be  controlled  to  a  very  large  extent 
by  judicious  watering  of  the  seed  bed.  In  most  cases  the  water  is 
applied  too  frequently  and  abundantly  and  the  spread  of  the  fungus 
thus  favored.  This  trouble  was  very  abundant  during  the  spring 
of  1909,  when  much  cloudy  weather  occurred. 

Anthracnose  or  "Tear  Stain"  (Collet otrichum) . — This  fungus 
seems  to  have  been  present  in  California  for  some  time,  but  previous 
to  1909  has  attracted  no  attention  as  affecting  the  fruit  seriously, 
occurring  only  occasionally  as  a  saprophyte  on  unhealthy  leaves  and 
twigs.  During  the  past  season,  however,  it  has  been  quite  abundant 
on  oranges  and  extremely  so  on  lemons  and  grapefruit  in  the  coast 
sections. 

Lemon. 

Brown  Rot  (Pythiacystis  citrophthora) . — Less  prevalent  than 
usual  in  1908  and  1909. 

Cottony  Mould  Rot  (Sclerotinia) . — Not  uncommon  in  curing 
houses. 

Gray  Mould  (Botrytis) . — Occurs  occasionally  in  storage  and  some- 
times causes  considerable  loss  under  cold  storage  conditions  at  low 
temperatures.  Causes  a  brownish,  soft  rot  of  the  rind,  more  or  less 
covered  with  a  considerable  growth  of  loose  gray  mould. 

Anthracnose  or  "Tear  Stain"  (C ollet otrichum) . — Quite  common 
in  coast  sections  in  1909,  causing  spots  on  the  rind  of  the  fruit.  In- 
fection apparently  favored  by  attacks  of  red  spider. 

Olive. 

Tuberculosis. — This  bacterial  disease  is  on  the  increase  in  certain 
sections  and  has  become  a  matter  of  serious  importance  in  those  re- 
gions. 


60  UNIVERSITY  OF  CALIFORNIA EXPERIMENT  STATION. 

Leaf  Spot  (Cycloconium  oleaginum) . — Apparently  rather  com- 
mon. 

Dry  Rot  of  fruit. — Cause  unknown.     Prevalent  in  1908. 

GUAVA. 

Russeting. — An  effect  on  the  fruit  in  San  Diego  County. 

VEGETABLES  AND  FIELD  CROPS. 

Asparagus. 

Rust. — Continues  to  some  extent  each  year.  Damage  by  floods 
in  the  principal  asparagus  regions  have  somewhat  overshadowed  the 
effects  of  the  rust.     Much  less  abundant  in  1908  and  1909. 

Sugar  Beet. 

Rust  (Uromyces) . — The  rust  was  extremely  abundant  during  the 
winter  of  1907-08  on  sugar  beets  growing  during  the  rainy  season. 
It  did  not  persist  after  the  rains  ceased. 

Curly  Top. — This  disease,  also  called  blight,  occurred  very  little 
in  1907,  but  came  on  in  some  sections  during  the  summer  of  1908. 

Downy  Mildew  (Peronospora  schachtii). — Found  in  Los  Angeles 
and  Orange  counties  in  the  spring  of  1909. 

Root  Rot  (Rhizoctonia) . — Caused  considerable  loss  in  young  seed- 
lings in  1908  and  1909. 

Celery. 

Leaf  Blight. — This  disease  occurred  disastrously  in  the  large 
Orange  County  celery  districts  during  the  season  of  1907-08.  Great 
losses  were  experienced  both  in  the  field  and  in  shipment.  The  dis- 
ease was  fully  as  prevalent  during  1908-09,  but  was  largely  controlled 
in  Orange  County  by  spraying,  as  described  on  page  42, 

Stem  Rot   (Sclerotinia) . — Found  in  1909.     Not  serious. 

Root  Rot  (Fusarium). — Occurred  only  in  extremely  wet  ground. 
Fungus  possibly  saprophytic. 

Potato. 

Early  Blight  (Altemaria) . — Found  in  Berkeley  and  reported 
elsewhere.     Not  serious. 

Late  Blight  (Phytophthora) . — Occurs  every  year  to  a  consider- 
able extent  on  winter  potatoes  grown  during  the  rainy  season  and 
on  the  summer  crop  in  foggy  sections  along  the  coast. 

Stem  Rot   {Fusarium). — Considerably  abundant  each  year. 


Bulletin  203.  REPORT  OF  PLANT  PATPIOLOGIST.  61 

Tomato. 

Winter  Blight  (Phytophthora  infestans). — Entirely  ruined  the 
late  crop  of  shipping  tomatoes  in  southern  California  in  October, 
1907.     Less  abundant  in  1908. 

Stem  Rot  (Sclerotinia)  and  Nematode  Root  Rot. — Observed  on 
greenhouse  plants  in  southern  California. 

Blossom  End  Rot. — Very  prevalent  in  1908.  The  origin  of  the 
disease  appears  to  be  connected  with  soil  moisture  conditions. 

Slimmer  Blight  or  Wilt  (Fusarium). — Almost  entirely  absent 
from  southern  California  in  1908,  but  quite  abundant  in  the  northern 
portion  of  the  State.  Apparently  connected  with  Fusarium  damping 
off  in  the  seed  bed.     Soil  in  the  field  does  not  carry  infection  from 

year  to  year. 

Egg  Plant. 

Stem  Blight  {Fusarium) . — A  dry  rot  of  the  stem  often  starting- 
above  ground  in  infection  through  a  wound.  This  plant  grows  to 
be  two  years  old  in  California  and  infection  by  this  disease  is  more 
common  during  the  winter. 

Sweet  Potato. 

Black  Rot  (Ceratocystis). — Found  in  1908  in  Orange  County  for 
the  first  time  in  California. 

Soft  Rot   (Rhizopus). — Quite  common. 

Sweet  Corn. 

Bacterial  Disease  (Bacterium  stewarti). — An  apparently  typical 
case  of  this  disease  was  found  in  southern  California  in  1909. 

Turnip. 

Black  Rot  (Bacterium  campestre) . — A  probable  case  found  in 
1909. 

Watermelon. 

Wilt    (Fusarium). — Abundant  in  old  fields   and  growing  worse. 

GRAINS  AND  FOEAGE  CROPS. 

Alfalfa. 

Downy  Mildew  (Peronospora  trifoliorum) . — Found  on  one  vol- 
unteer plant  in  1909. 

Alfalfa  Crown  Gall  (Urophlyctis  alfalfae). — This  unusual  disease 
was  found  in  the  State  for  the  first  time  during  1909,  and,  so  far  as 
we  know,  has  not  been  observed  heretofore  in  this  country.  It  has 
been  collected  in  wet  regions  in  Yolo  and  Stanislaus  counties,  and 
doubtless  occurs  elsewhere. 


62  UNIVERSITY  OF  CALIFORNIA — EXPERIMENT  STATION. 


Fig.  23. — Orowngall  of  alfalfa. 


Bulletin  203.  REPORT  OP  PLANT  PATHOLOGIST.  63 

NUT,  FOKEST  AND  SHADE  TREES. 

Madron  e. 

Leaf  Spot   (Sphaerella  arbuticola). — Quite  abundant  and  disfig- 
uring. 

Sycamore. 

Sycamore  Blight    (Gloeosporium  nervisequum) . — Very  prevalent 

in  1909. 

Palm  (Washingtonia) . 

Leaf  Spot    (Auerswaldia  sp.). — Noticeable  in  parts  of  southern 
California. 

Walnut. 

Bacteriosis. — Very  prevalent  in  1907.     Less  abundant  in  1908  in 
most  sections.     Quite  common  in  1909. 

Blue  Gum  (Eucalyptus). 

Leaf  Spot  (Hendersonia  sp.) . — Observed  in  several  cases  on  young 
leaves. 

FLOEAL   AND  OENAMENTAL. 

Carnation. 

Leaf  Spot   (Heterosporium) . — Rather  common. 
(Septoria) . — Occasionally  found. 

Oleander. 

Leaf  Spot  (Macrosporium  nerium). — From  Fresno. 

Sunflower. 

Damping  Off  and  Stem  Rot  (Botrytis). — Observed  in  one  case. 

Rose. 

Mildew,  Rust  and  Black  Spot. — All  unusually  abundant  during 
the  spring  of  1909. 


Station  Publications  Available  for  Distribution. 


1896. 

1897. 

1900. 
1902. 
1903. 
1904. 


ith  data  regarding  the 


EEPOETS. 

Report  of  the  Viticultural  Work  during  the  seasons  1887-93, 

Vintages   of    1894-95. 
Resistant  Vines,  their  Selection,  Adaptation,   and  Grafting.      Appendix  to  Viticultural 

Report  for  1896. 
Report  of  the  Agricultural  Experiment   Station  for  the  year   1897-98. 
Report  of  the  Agricultural  Experiment   Station  for   1898-1901. 
Report  of  the  Agricultural  Experiment   Station  for   1901-03. 
Twenty-second  Report  of  the  Agricultural  Experiment  Station  for   1903-04. 


BULLETINS. 


Reprint.      Endurance    of    Drought    in    Soils 

of   the   Arid   Region. 
No.  128.      Nature,   Value  and  Utilization  of 

Alkali  Lands,   and  Tolerance  of 

Alkali.      (Revised   and   Reprint, 

1905.) 
133.     Tolerance    of    Alkali    by    Various 

Cultures. 
140.      Lands    of    the    Colorado    Delta    in 

Salton   Basin,    and   Supplement. 
142.      Grasshoppers    in    California. 
147.      Culture  Work  of  the  Sub-stations. 

149.  California    Sugar    Industry. 

150.  The    Value    of    Oak    Leaves    for 

Forage. 

151.  Arsenical  Insecticides. 

153.  Spraying  with  Distillates. 

154.  Sulfur  Sprays  for  Red  Spider. 
156.      Fowl  Cholera. 

159.  Contribution     to     the     Study     of 

Fermentation. 

160.  The   Hop   Aphis. 

161.  Tuberculosis  in  Fowls.    (Reprint.) 

162.  Commercial  Fertilizers.      (Dec.    1, 

1904.) 

163.  Pear   Scab. 

165.      Asparagus    and    Asparagus    Rust 
in   California. 

167.  Manufacture    of    Dry    Wines     in 

Hot  Countries. 

168.  Observations   on    Some   Vine   Dis- 

eases   in    Sonoma    County. 

169.  Tolerance   of  the   Sugar   Beet   for 

Alkali. 

170.  Studies  in   Grasshopper  Control. 

171.  Commercial  Fertilizers.     (June  30, 

1905.) 

172.  Further  Experience  in  Asparagus 

Rust   Control. 
174.      A   New  Wine-cooling  Machine. 


176.  Sugar   Beets   in  the   San   Joaquin 

Valley. 

177.  A    New    Method    of    Making    Dry 

Red  Wine. 

178.  Mosquito   Control. 

179.  Commercial     Fertilizers.        (June, 

1906.) 

180.  Resistant  Vineyards. 

181.  The   Selection   of    Seed- Wheat. 

182.  Analysis     of     Paris     Green     and 

Lead  Arsenate.  Proposed  In- 
secticide Law. 

183.  The  California  Tussock-moth. 

184.  Report    of    the    Plant    Pathologist 

to  July  1,   1906. 

185.  Report  of  Progress  in  Cereal  In- 

vestigations. 

186.  The  Oidium  of  the  Vine. 

187.  Commercial     Fertilizers.        (Janu- 

ary,   1907.) 

188.  Lining  of  Ditches  and  Reservoirs 

to  Prevent  Seepage  and  Losses. 

189.  Commercial     Fertilizers.        (June, 

1907.) 

190.  The  Brown  Rot  of  the  Lemon. 

191.  California  Peach  Blight. 

192.  Insects   Injurious   to  the  Vine   in 

California. 

193.  The   Best   Wine   Grapes   for   Cali- 

fornia; Pruning  Young  Vines; 
Pruning  the   Sultanina. 

194.  Commercial     Fertilizers.        (Dec, 

1907.) 

195.  The  California  Grape  Root-worm. 

197.  Grape  Culture  in  California;   Im- 

proved Methods  of  Wine  Mak- 
ing; Yeasts  from  California 
Grapes. 

198.  The   Grape   Leaf-Hopper. 

199.  The  Bovine  Tuberculosis. 


CIECULAES. 


No.     1.      Texas   Fever. 

2.  Blackleg. 

3.  Hog  Cholera. 

4.  Anthrax 

5.  Contagious  Abortion  in  Cows. 
7.      Remedies  for  Insects. 

9.      Asparagus   Rust. 

10.  Reading   Course   in   Economic    En- 

tomology.      (Revision.) 

11.  Fumigation  Practice. 

12.  Silk  Culture. 

15.      Recent    Problems    in    Agriculture. 
What  a  University  Farm  is  For. 

17.  Why        Agriculture        Should       be 

Taught  in  the  Public   Schools. 

18.  Caterpillars   on   Oaks. 

19.  Disinfection   of    Stables. 

21.      The    Advancement    of    Agricultural 

Education. 
24.      Olive  Pickling. 
26.      Selection   and  Preparation  of  Vine 

Cuttings. 


27       Marlv    Subsoils    and    the    Chlorosis 
or   Yellowing   of   Citrus   Trees. 

28.  A  Preliminary  Progress  Report  of 

Cereal    Investigations,    1905-07. 

29.  Preliminary      Announcement      con- 

cerning Instruction  in  Practical 
Agriculture  upon  the  University 
Farm,   Davisville,   Cal. 

30.  White  Fly  in  California. 

31.  The    Agricultural    College    and    Its 

Relationship  to  the  Scheme  of 
National  Education. 

32.  White  Fly  Eradication. 

33.  Packing    Prunes    in    Cans.       Cane 

Sugar  vs.  Beet  Sugar. 

34.  California  State  Farmers'  Institute 

at  the  University   Farm. 

35.  Southern     California     Pathological 

Laboratory  and  Citrus  Experi- 
ment  Station. 

36.  Analyses    of    Fertilizers    for     Con- 

sumers. 


Copies  may  be  had  on  application  to  Director  of  Experiment  Station,  Berkeley,  Cal. 


